165501491 has 4 divisors (see below), whose sum is σ = 172697232. Its totient is φ = 158305752.

The previous prime is 165501389. The next prime is 165501499. The reversal of 165501491 is 194105561.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 194105561 = 13 ⋅14931197.

It is a cyclic number.

It is not a de Polignac number, because 165501491 - 2²² = 161307187 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165501499) 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, 3597836 + ... + 3597881.

It is an arithmetic number, because the mean of its divisors is an integer number (43174308).

Almost surely, 2^165501491 is an apocalyptic number.

165501491 is a deficient number, since it is larger than the sum of its proper divisors (7195741).

165501491 is an equidigital number, since it uses as much as digits as its factorization.

165501491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7195740.

The product of its (nonzero) digits is 5400, while the sum is 32.

The square root of 165501491 is about 12864.7382794987. The cubic root of 165501491 is about 549.0357661864.

The spelling of 165501491 in words is "one hundred sixty-five million, five hundred one thousand, four hundred ninety-one".