161557499 has 4 divisors (see below), whose sum is σ = 161648520. Its totient is φ = 161466480.

The previous prime is 161557469. The next prime is 161557519. The reversal of 161557499 is 994755161.

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

It is a cyclic number.

It is not a de Polignac number, because 161557499 - 2⁸ = 161557243 is a prime.

It is a super-2 number, since 2×161557499² = 52201650966270002, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161557469) 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, 42794 + ... + 46415.

It is an arithmetic number, because the mean of its divisors is an integer number (40412130).

Almost surely, 2^161557499 is an apocalyptic number.

161557499 is a deficient number, since it is larger than the sum of its proper divisors (91021).

161557499 is an equidigital number, since it uses as much as digits as its factorization.

161557499 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91020.

The product of its digits is 340200, while the sum is 47.

The square root of 161557499 is about 12710.5270937125. The cubic root of 161557499 is about 544.6393809966.

The spelling of 161557499 in words is "one hundred sixty-one million, five hundred fifty-seven thousand, four hundred ninety-nine".