15561601056 has 36 divisors (see below), whose sum is σ = 44253303822. Its totient is φ = 5187200256.

The previous prime is 15561601031. The next prime is 15561601079. The reversal of 15561601056 is 65010616551.

It can be written as a sum of positive squares in only one way, i.e., 13669351056 + 1892250000 = 116916^2 + 43500^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×15561601056² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 15561601056.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 27016381 + ... + 27016956.

Almost surely, 2^15561601056 is an apocalyptic number.

15561601056 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

15561601056 is an abundant number, since it is smaller than the sum of its proper divisors (28691702766).

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

15561601056 is a wasteful number, since it uses less digits than its factorization.

15561601056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54033353 (or 54033342 counting only the distinct ones).

The product of its (nonzero) digits is 27000, while the sum is 36.

The spelling of 15561601056 in words is "fifteen billion, five hundred sixty-one million, six hundred one thousand, fifty-six".