620557921 has 9 divisors (see below), whose sum is σ = 643443411. Its totient is φ = 598461864.

The previous prime is 620557913. The next prime is 620557939. The reversal of 620557921 is 129755026.

The square root of 620557921 is 24911.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 325405521 + 295152400 = 18039^2 + 17180^2 .

It is not a de Polignac number, because 620557921 - 2³ = 620557913 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (620557981) 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 8 ways as a sum of consecutive naturals, for example, 721990 + ... + 722848.

Almost surely, 2^620557921 is an apocalyptic number.

620557921 is the 24911-st square number.

620557921 is the 12456-th centered octagonal number.

It is an amenable number.

620557921 is a deficient number, since it is larger than the sum of its proper divisors (22885490).

620557921 is an frugal number, since it uses more digits than its factorization.

620557921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1776 (or 888 counting only the distinct ones).

The product of its (nonzero) digits is 37800, while the sum is 37.

The cubic root of 620557921 is about 852.9575959976.

The spelling of 620557921 in words is "six hundred twenty million, five hundred fifty-seven thousand, nine hundred twenty-one".