1221921936 has 75 divisors (see below), whose sum is σ = 3540242563. Its totient is φ = 406887840.

The previous prime is 1221921923. The next prime is 1221921949. The reversal of 1221921936 is 6391291221.

The square root of 1221921936 is 34956.

It is a perfect power (a square), and thus also a powerful number.

It is an interprime number because it is at equal distance from previous prime (1221921923) and next prime (1221921949).

It is a super-3 number, since 3×1221921936³ (a number of 28 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1221921936.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 1257931 + ... + 1258901.

Almost surely, 2^1221921936 is an apocalyptic number.

1221921936 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

1221921936 is the 34956-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1221921936

1221921936 is an abundant number, since it is smaller than the sum of its proper divisors (2318320627).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1221921936 is an frugal number, since it uses more digits than its factorization.

1221921936 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1962 (or 976 counting only the distinct ones).

The product of its digits is 11664, while the sum is 36.

The cubic root of 1221921936 is about 1069.0905411570.

Multiplying 1221921936 by its sum of digits (36), we get a square (43989189696 = 209736²).

1221921936 divided by its sum of digits (36) gives a square (33942276 = 5826²).

Multiplying 1221921936 by its product of digits (11664), we get a square (14252497461504 = 3775248²).

The spelling of 1221921936 in words is "one billion, two hundred twenty-one million, nine hundred twenty-one thousand, nine hundred thirty-six".