161561215 has 4 divisors (see below), whose sum is σ = 193873464. Its totient is φ = 129248968.

The previous prime is 161561209. The next prime is 161561221. The reversal of 161561215 is 512165161.

It is a happy number.

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

It is an interprime number because it is at equal distance from previous prime (161561209) and next prime (161561221).

It is a cyclic number.

It is not a de Polignac number, because 161561215 - 2³ = 161561207 is a prime.

It is a super-2 number, since 2×161561215² = 52204052384552450, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16156117 + ... + 16156126.

It is an arithmetic number, because the mean of its divisors is an integer number (48468366).

Almost surely, 2^161561215 is an apocalyptic number.

161561215 is a deficient number, since it is larger than the sum of its proper divisors (32312249).

161561215 is an equidigital number, since it uses as much as digits as its factorization.

161561215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32312248.

The product of its digits is 1800, while the sum is 28.

The square root of 161561215 is about 12710.6732709168. The cubic root of 161561215 is about 544.6435567327.

It can be divided in two parts, 16156 and 1215, that added together give a palindrome (17371).

The spelling of 161561215 in words is "one hundred sixty-one million, five hundred sixty-one thousand, two hundred fifteen".