1221613536 has 384 divisors, whose sum is σ = 4060191744. Its totient is φ = 316293120.

The previous prime is 1221613501. The next prime is 1221613567. The reversal of 1221613536 is 6353161221.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 16734396 + ... + 16734468.

It is an arithmetic number, because the mean of its divisors is an integer number (10573416).

Almost surely, 2^1221613536 is an apocalyptic number.

1221613536 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1221613536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2030095872).

1221613536 is an abundant number, since it is smaller than the sum of its proper divisors (2838578208).

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

1221613536 is a wasteful number, since it uses less digits than its factorization.

1221613536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 186 (or 178 counting only the distinct ones).

The product of its digits is 6480, while the sum is 30.

The square root of 1221613536 is about 34951.5884617566. The cubic root of 1221613536 is about 1069.0005912577. Note that the first 3 decimals are identical.

Adding to 1221613536 its reverse (6353161221), we get a palindrome (7574774757).

It can be divided in two parts, 12216 and 13536, that added together give a palindrome (25752).

The spelling of 1221613536 in words is "one billion, two hundred twenty-one million, six hundred thirteen thousand, five hundred thirty-six".