161772961 has 27 divisors (see below), whose sum is σ = 199244241. Its totient is φ = 130954824.

The previous prime is 161772953. The next prime is 161772971. The reversal of 161772961 is 169277161.

The square root of 161772961 is 12719.

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

It is not a de Polignac number, because 161772961 - 2³ = 161772953 is a prime.

It is not an unprimeable number, because it can be changed into a prime (161772931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 2047720 + ... + 2047798.

Almost surely, 2^161772961 is an apocalyptic number.

161772961 is the 12719-th square number.

161772961 is the 6360-th centered octagonal number.

It is an amenable number.

161772961 is a deficient number, since it is larger than the sum of its proper divisors (37471280).

161772961 is an frugal number, since it uses more digits than its factorization.

161772961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 218 (or 109 counting only the distinct ones).

The product of its digits is 31752, while the sum is 40.

The cubic root of 161772961 is about 544.8813938237.

The spelling of 161772961 in words is "one hundred sixty-one million, seven hundred seventy-two thousand, nine hundred sixty-one".