161631656 has 8 divisors (see below), whose sum is σ = 303059370. Its totient is φ = 80815824.

The previous prime is 161631653. The next prime is 161631667. The reversal of 161631656 is 656136161.

It can be written as a sum of positive squares in only one way, i.e., 84015556 + 77616100 = 9166^2 + 8810^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a super-2 number, since 2×161631656² = 52249584442604672, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (161631653) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10101971 + ... + 10101986.

Almost surely, 2^161631656 is an apocalyptic number.

It is an amenable number.

161631656 is a deficient number, since it is larger than the sum of its proper divisors (141427714).

161631656 is a wasteful number, since it uses less digits than its factorization.

161631656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20203963 (or 20203959 counting only the distinct ones).

The product of its digits is 19440, while the sum is 35.

The square root of 161631656 is about 12713.4439079268. The cubic root of 161631656 is about 544.7227004438.

The spelling of 161631656 in words is "one hundred sixty-one million, six hundred thirty-one thousand, six hundred fifty-six".