161651166625 has 32 divisors (see below), whose sum is σ = 220820929056. Its totient is φ = 117416160000.

The previous prime is 161651166617. The next prime is 161651166629. The reversal of 161651166625 is 526661156161.

It can be written as a sum of positive squares in 16 ways, for example, as 158302924129 + 3348242496 = 397873^2 + 57864^2 .

It is not a de Polignac number, because 161651166625 - 2³ = 161651166617 is a prime.

It is a super-2 number, since 2×161651166625² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (161651166629) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 716266 + ... + 914515.

It is an arithmetic number, because the mean of its divisors is an integer number (6900654033).

Almost surely, 2^161651166625 is an apocalyptic number.

It is an amenable number.

161651166625 is a deficient number, since it is larger than the sum of its proper divisors (59169762431).

161651166625 is a wasteful number, since it uses less digits than its factorization.

161651166625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1630870 (or 1630860 counting only the distinct ones).

The product of its digits is 388800, while the sum is 46.

The spelling of 161651166625 in words is "one hundred sixty-one billion, six hundred fifty-one million, one hundred sixty-six thousand, six hundred twenty-five".