165544621 has 4 divisors (see below), whose sum is σ = 180594144. Its totient is φ = 150495100.

The previous prime is 165544601. The next prime is 165544637. The reversal of 165544621 is 126445561.

165544621 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 126445561 = 11 ⋅11495051.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-165544621 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165544601) 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, 7524745 + ... + 7524766.

It is an arithmetic number, because the mean of its divisors is an integer number (45148536).

Almost surely, 2^165544621 is an apocalyptic number.

165544621 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

165544621 is a deficient number, since it is larger than the sum of its proper divisors (15049523).

165544621 is a wasteful number, since it uses less digits than its factorization.

165544621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15049522.

The product of its digits is 28800, while the sum is 34.

The square root of 165544621 is about 12866.4144578045. The cubic root of 165544621 is about 549.0834552953.

The spelling of 165544621 in words is "one hundred sixty-five million, five hundred forty-four thousand, six hundred twenty-one".