161551917 has 12 divisors (see below), whose sum is σ = 235535040. Its totient is φ = 106694088.

The previous prime is 161551913. The next prime is 161551921. The reversal of 161551917 is 719155161.

161551917 is a `hidden beast` number, since 16 + 1 + 551 + 91 + 7 = 666.

It is an interprime number because it is at equal distance from previous prime (161551913) and next prime (161551921).

It is not a de Polignac number, because 161551917 - 2² = 161551913 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161551913) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 82917 + ... + 84842.

It is an arithmetic number, because the mean of its divisors is an integer number (19627920).

Almost surely, 2^161551917 is an apocalyptic number.

It is an amenable number.

161551917 is a deficient number, since it is larger than the sum of its proper divisors (73983123).

161551917 is a wasteful number, since it uses less digits than its factorization.

161551917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 167872 (or 167869 counting only the distinct ones).

The product of its digits is 9450, while the sum is 36.

The square root of 161551917 is about 12710.3075100487. The cubic root of 161551917 is about 544.6331082825.

The spelling of 161551917 in words is "one hundred sixty-one million, five hundred fifty-one thousand, nine hundred seventeen".