1221578156 has 12 divisors (see below), whose sum is σ = 2138535168. Its totient is φ = 610568112.

The previous prime is 1221578143. The next prime is 1221578179. The reversal of 1221578156 is 6518751221.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 42476 + ... + 65171.

It is an arithmetic number, because the mean of its divisors is an integer number (178211264).

Almost surely, 2^1221578156 is an apocalyptic number.

It is an amenable number.

1221578156 is a deficient number, since it is larger than the sum of its proper divisors (916957012).

1221578156 is a wasteful number, since it uses less digits than its factorization.

1221578156 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110488 (or 110486 counting only the distinct ones).

The product of its digits is 33600, while the sum is 38.

The square root of 1221578156 is about 34951.0823294501. The cubic root of 1221578156 is about 1068.9902711347.

The spelling of 1221578156 in words is "one billion, two hundred twenty-one million, five hundred seventy-eight thousand, one hundred fifty-six".