1221372856 has 32 divisors (see below), whose sum is σ = 2500948080. Its totient is φ = 554572800.

The previous prime is 1221372853. The next prime is 1221372913. The reversal of 1221372856 is 6582731221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221372851) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 80776 + ... + 94696.

Almost surely, 2^1221372856 is an apocalyptic number.

It is an amenable number.

1221372856 is an abundant number, since it is smaller than the sum of its proper divisors (1279575224).

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

1221372856 is a wasteful number, since it uses less digits than its factorization.

1221372856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14935 (or 14931 counting only the distinct ones).

The product of its digits is 40320, while the sum is 37.

The square root of 1221372856 is about 34948.1452440612. The cubic root of 1221372856 is about 1068.9303824851.

The spelling of 1221372856 in words is "one billion, two hundred twenty-one million, three hundred seventy-two thousand, eight hundred fifty-six".