655625561621 has 4 divisors (see below), whose sum is σ = 664606733772. Its totient is φ = 646644389472.

The previous prime is 655625561611. The next prime is 655625561627. The reversal of 655625561621 is 126165526556.

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

It can be written as a sum of positive squares in 2 ways, for example, as 493240740721 + 162384820900 = 702311^2 + 402970^2 .

It is a cyclic number.

It is not a de Polignac number, because 655625561621 - 2³⁰ = 654551819797 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 655625561621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (655625561627) 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, 4490585966 + ... + 4490586111.

It is an arithmetic number, because the mean of its divisors is an integer number (166151683443).

Almost surely, 2^655625561621 is an apocalyptic number.

It is an amenable number.

655625561621 is a deficient number, since it is larger than the sum of its proper divisors (8981172151).

655625561621 is an equidigital number, since it uses as much as digits as its factorization.

655625561621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8981172150.

The product of its digits is 3240000, while the sum is 50.

The spelling of 655625561621 in words is "six hundred fifty-five billion, six hundred twenty-five million, five hundred sixty-one thousand, six hundred twenty-one".