1221801408 has 140 divisors (see below), whose sum is σ = 3642224872. Its totient is φ = 404974080.

The previous prime is 1221801397. The next prime is 1221801461. The reversal of 1221801408 is 8041081221.

It is a Harshad number since it is a multiple of its sum of digits (27).

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 19 ways as a sum of consecutive naturals, for example, 1093266 + ... + 1094382.

Almost surely, 2^1221801408 is an apocalyptic number.

1221801408 is a gapful number since it is divisible by the number (18) 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 1221801408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1821112436).

1221801408 is an abundant number, since it is smaller than the sum of its proper divisors (2420423464).

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

1221801408 is a wasteful number, since it uses less digits than its factorization.

1221801408 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1352 (or 1333 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 27.

The square root of 1221801408 is about 34954.2759616045. The cubic root of 1221801408 is about 1069.0553889982.

Adding to 1221801408 its reverse (8041081221), we get a palindrome (9262882629).

The spelling of 1221801408 in words is "one billion, two hundred twenty-one million, eight hundred one thousand, four hundred eight".