161657725 has 6 divisors (see below), whose sum is σ = 200455610. Its totient is φ = 129326160.

The previous prime is 161657701. The next prime is 161657753. The reversal of 161657725 is 527756161.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 799236 + 160858489 = 894^2 + 12683^2 .

It is not a de Polignac number, because 161657725 - 2⁵ = 161657693 is a prime.

It is a super-2 number, since 2×161657725² = 52266440104351250, which contains 22 as substring.

It is a congruent number.

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, 3233130 + ... + 3233179.

Almost surely, 2^161657725 is an apocalyptic number.

It is an amenable number.

161657725 is a deficient number, since it is larger than the sum of its proper divisors (38797885).

161657725 is an equidigital number, since it uses as much as digits as its factorization.

161657725 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6466319 (or 6466314 counting only the distinct ones).

The product of its digits is 88200, while the sum is 40.

The square root of 161657725 is about 12714.4691198650. The cubic root of 161657725 is about 544.7519843375.

The spelling of 161657725 in words is "one hundred sixty-one million, six hundred fifty-seven thousand, seven hundred twenty-five".