65566621 has 4 divisors (see below), whose sum is σ = 65740000. Its totient is φ = 65393244.

The previous prime is 65566609. The next prime is 65566639. The reversal of 65566621 is 12666556.

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 65566621 - 2¹³ = 65558429 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 (65566681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 86121 + ... + 86878.

It is an arithmetic number, because the mean of its divisors is an integer number (16435000).

Almost surely, 2^65566621 is an apocalyptic number.

It is an amenable number.

65566621 is a deficient number, since it is larger than the sum of its proper divisors (173379).

65566621 is a wasteful number, since it uses less digits than its factorization.

65566621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 173378.

The product of its digits is 64800, while the sum is 37.

The square root of 65566621 is about 8097.3218412016. The cubic root of 65566621 is about 403.2375192270.

It can be divided in two parts, 655 and 66621, that added together give a palindrome (67276).

The spelling of 65566621 in words is "sixty-five million, five hundred sixty-six thousand, six hundred twenty-one".