165621520 has 40 divisors (see below), whose sum is σ = 389725056. Its totient is φ = 65447808.

The previous prime is 165621457. The next prime is 165621553. The reversal of 165621520 is 25126561.

It is a tau number, because it is divible by the number of its divisors (40).

It is a super-2 number, since 2×165621520² = 54860975774220800, which contains 22 as substring.

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, 5832 + ... + 19111.

Almost surely, 2^165621520 is an apocalyptic number.

165621520 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

165621520 is an abundant number, since it is smaller than the sum of its proper divisors (224103536).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

165621520 is a wasteful number, since it uses less digits than its factorization.

165621520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25039 (or 25033 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 28.

The square root of 165621520 is about 12869.4024725315. The cubic root of 165621520 is about 549.1684624515.

The spelling of 165621520 in words is "one hundred sixty-five million, six hundred twenty-one thousand, five hundred twenty".