1221554156 has 24 divisors (see below), whose sum is σ = 2253294960. Its totient is φ = 577843200.

The previous prime is 1221554141. The next prime is 1221554167. The reversal of 1221554156 is 6514551221.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 47276 + ... + 68396.

It is an arithmetic number, because the mean of its divisors is an integer number (93887290).

Almost surely, 2^1221554156 is an apocalyptic number.

It is an amenable number.

1221554156 is a deficient number, since it is larger than the sum of its proper divisors (1031740804).

1221554156 is a wasteful number, since it uses less digits than its factorization.

1221554156 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21905 (or 21903 counting only the distinct ones).

The product of its digits is 12000, while the sum is 32.

The square root of 1221554156 is about 34950.7389907567. The cubic root of 1221554156 is about 1068.9832703725.

The spelling of 1221554156 in words is "one billion, two hundred twenty-one million, five hundred fifty-four thousand, one hundred fifty-six".