655123621 has 4 divisors (see below), whose sum is σ = 655583500. Its totient is φ = 654663744.

The previous prime is 655123613. The next prime is 655123631. The reversal of 655123621 is 126321556.

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 127916100 + 527207521 = 11310^2 + 22961^2 .

It is a cyclic number.

It is not a de Polignac number, because 655123621 - 2³ = 655123613 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 (655123631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 227796 + ... + 230653.

It is an arithmetic number, because the mean of its divisors is an integer number (163895875).

Almost surely, 2^655123621 is an apocalyptic number.

It is an amenable number.

655123621 is a deficient number, since it is larger than the sum of its proper divisors (459879).

655123621 is a wasteful number, since it uses less digits than its factorization.

655123621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 459878.

The product of its digits is 10800, while the sum is 31.

The square root of 655123621 is about 25595.3828062797. The cubic root of 655123621 is about 868.5091925708.

The spelling of 655123621 in words is "six hundred fifty-five million, one hundred twenty-three thousand, six hundred twenty-one".