161670891 has 4 divisors (see below), whose sum is σ = 215561192. Its totient is φ = 107780592.

The previous prime is 161670877. The next prime is 161670931. The reversal of 161670891 is 198076161.

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

It is not a de Polignac number, because 161670891 - 2⁶ = 161670827 is a prime.

It is a super-2 number, since 2×161670891² = 52274953993467762, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161670491) 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, 26945146 + ... + 26945151.

It is an arithmetic number, because the mean of its divisors is an integer number (53890298).

Almost surely, 2^161670891 is an apocalyptic number.

161670891 is a deficient number, since it is larger than the sum of its proper divisors (53890301).

161670891 is an equidigital number, since it uses as much as digits as its factorization.

161670891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53890300.

The product of its (nonzero) digits is 18144, while the sum is 39.

The square root of 161670891 is about 12714.9868658996. The cubic root of 161670891 is about 544.7667728047.

The spelling of 161670891 in words is "one hundred sixty-one million, six hundred seventy thousand, eight hundred ninety-one".