1221855936 has 56 divisors (see below), whose sum is σ = 3694663680. Its totient is φ = 349101312.

The previous prime is 1221855919. The next prime is 1221855997. The reversal of 1221855936 is 6395581221.

It is a tau number, because it is divible by the number of its divisors (56).

It is a Harshad number since it is a multiple of its sum of digits (42).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 453216 + ... + 455903.

Almost surely, 2^1221855936 is an apocalyptic number.

1221855936 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

1221855936 is an abundant number, since it is smaller than the sum of its proper divisors (2472807744).

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

1221855936 is an equidigital number, since it uses as much as digits as its factorization.

1221855936 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 909141 (or 909131 counting only the distinct ones).

The product of its digits is 129600, while the sum is 42.

The square root of 1221855936 is about 34955.0559433110. The cubic root of 1221855936 is about 1069.0712924516.

The spelling of 1221855936 in words is "one billion, two hundred twenty-one million, eight hundred fifty-five thousand, nine hundred thirty-six".