15985355352561 has 45 divisors (see below), whose sum is σ = 27778466400201. Its totient is φ = 9134344838808.

The previous prime is 15985355352521. The next prime is 15985355352583. The reversal of 15985355352561 is 16525355358951.

The square root of 15985355352561 is 3998169.

It is a perfect power (a square), and thus also a powerful number.

15985355352561 is a `hidden beast` number, since 1 + 5 + 9 + 8 + 5 + 35 + 5 + 35 + 2 + 561 = 666.

It is not a de Polignac number, because 15985355352561 - 2²³ = 15985346963953 is a prime.

It is a super-2 number, since 2×15985355352561² (a number of 27 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (15985355352521) by changing a digit.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 251852916 + ... + 251916378.

Almost surely, 2^{15985355352561} is an apocalyptic number.

15985355352561 is the 3998169-th square number.

15985355352561 is the 1999085-th centered octagonal number.

It is an amenable number.

15985355352561 is a deficient number, since it is larger than the sum of its proper divisors (11793111047640).

15985355352561 is an frugal number, since it uses more digits than its factorization.

15985355352561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 126952 (or 63473 counting only the distinct ones).

The product of its digits is 121500000, while the sum is 63.

The spelling of 15985355352561 in words is "fifteen trillion, nine hundred eighty-five billion, three hundred fifty-five million, three hundred fifty-two thousand, five hundred sixty-one".