161515657 has 4 divisors (see below), whose sum is σ = 171016596. Its totient is φ = 152014720.

The previous prime is 161515643. The next prime is 161515663. The reversal of 161515657 is 756515161.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 43771456 + 117744201 = 6616^2 + 10851^2 .

It is a cyclic number.

It is not a de Polignac number, because 161515657 - 2¹¹ = 161513609 is a prime.

It is a super-2 number, since 2×161515657² = 52174614912283298, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161515357) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4750444 + ... + 4750477.

It is an arithmetic number, because the mean of its divisors is an integer number (42754149).

Almost surely, 2^161515657 is an apocalyptic number.

161515657 is a gapful number since it is divisible by the number (17) formed by its first and last digit.

It is an amenable number.

161515657 is a deficient number, since it is larger than the sum of its proper divisors (9500939).

161515657 is an equidigital number, since it uses as much as digits as its factorization.

161515657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9500938.

The product of its digits is 31500, while the sum is 37.

The square root of 161515657 is about 12708.8810286351. The cubic root of 161515657 is about 544.5923579682.

The spelling of 161515657 in words is "one hundred sixty-one million, five hundred fifteen thousand, six hundred fifty-seven".