165920811751 has 4 divisors (see below), whose sum is σ = 173134760112. Its totient is φ = 158706863392.

The previous prime is 165920811697. The next prime is 165920811761. The reversal of 165920811751 is 157118029561.

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

It is a cyclic number.

It is not a de Polignac number, because 165920811751 - 2²⁷ = 165786594023 is a prime.

It is a super-2 number, since 2×165920811751² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165920811761) 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, 3606974146 + ... + 3606974191.

It is an arithmetic number, because the mean of its divisors is an integer number (43283690028).

Almost surely, 2^165920811751 is an apocalyptic number.

165920811751 is a deficient number, since it is larger than the sum of its proper divisors (7213948361).

165920811751 is an equidigital number, since it uses as much as digits as its factorization.

165920811751 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7213948360.

The product of its (nonzero) digits is 151200, while the sum is 46.

The spelling of 165920811751 in words is "one hundred sixty-five billion, nine hundred twenty million, eight hundred eleven thousand, seven hundred fifty-one".