165720731 has 16 divisors (see below), whose sum is σ = 187204608. Its totient is φ = 145396800.

The previous prime is 165720721. The next prime is 165720733. The reversal of 165720731 is 137027561.

165720731 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 165720731 - 2²⁶ = 98611867 is a prime.

It is a super-2 number, since 2×165720731² = 54926721366348722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165720733) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 35546 + ... + 39936.

It is an arithmetic number, because the mean of its divisors is an integer number (11700288).

Almost surely, 2^165720731 is an apocalyptic number.

165720731 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

165720731 is a deficient number, since it is larger than the sum of its proper divisors (21483877).

165720731 is a wasteful number, since it uses less digits than its factorization.

165720731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4522.

The product of its (nonzero) digits is 8820, while the sum is 32.

The square root of 165720731 is about 12873.2564256291. The cubic root of 165720731 is about 549.2780952999.

The spelling of 165720731 in words is "one hundred sixty-five million, seven hundred twenty thousand, seven hundred thirty-one".