65165721 has 4 divisors (see below), whose sum is σ = 86887632. Its totient is φ = 43443812.

The previous prime is 65165719. The next prime is 65165747. The reversal of 65165721 is 12756156.

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.

It is a cyclic number.

It is not a de Polignac number, because 65165721 - 2¹ = 65165719 is a prime.

It is not an unprimeable number, because it can be changed into a prime (65165701) 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, 10860951 + ... + 10860956.

It is an arithmetic number, because the mean of its divisors is an integer number (21721908).

Almost surely, 2^65165721 is an apocalyptic number.

It is an amenable number.

65165721 is a deficient number, since it is larger than the sum of its proper divisors (21721911).

65165721 is a wasteful number, since it uses less digits than its factorization.

65165721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21721910.

The product of its digits is 12600, while the sum is 33.

The square root of 65165721 is about 8072.5287859505. The cubic root of 65165721 is about 402.4139877678.

The spelling of 65165721 in words is "sixty-five million, one hundred sixty-five thousand, seven hundred twenty-one".