165720813 has 8 divisors (see below), whose sum is σ = 221043168. Its totient is φ = 110439504.

The previous prime is 165720809. The next prime is 165720829. The reversal of 165720813 is 318027561.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 165720813 - 2² = 165720809 is a prime.

It is a super-2 number, since 2×165720813² = 54926775722761938, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165720833) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 895 + ... + 18227.

It is an arithmetic number, because the mean of its divisors is an integer number (27630396).

Almost surely, 2^165720813 is an apocalyptic number.

It is an amenable number.

165720813 is a deficient number, since it is larger than the sum of its proper divisors (55322355).

165720813 is a wasteful number, since it uses less digits than its factorization.

165720813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20523.

The product of its (nonzero) digits is 10080, while the sum is 33.

The square root of 165720813 is about 12873.2596105260. The cubic root of 165720813 is about 549.2781858957.

The spelling of 165720813 in words is "one hundred sixty-five million, seven hundred twenty thousand, eight hundred thirteen".