165491978 has 16 divisors (see below), whose sum is σ = 251709120. Its totient is φ = 81596256.

The previous prime is 165491939. The next prime is 165491987. The reversal of 165491978 is 879194561.

165491978 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 48203 + ... + 51521.

It is an arithmetic number, because the mean of its divisors is an integer number (15731820).

Almost surely, 2^165491978 is an apocalyptic number.

165491978 is a deficient number, since it is larger than the sum of its proper divisors (86217142).

165491978 is a wasteful number, since it uses less digits than its factorization.

165491978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3661.

The product of its digits is 544320, while the sum is 50.

The square root of 165491978 is about 12864.3685426064. The cubic root of 165491978 is about 549.0252464880.

The spelling of 165491978 in words is "one hundred sixty-five million, four hundred ninety-one thousand, nine hundred seventy-eight".