621720522 has 80 divisors (see below), whose sum is σ = 1421667720. Its totient is φ = 203046912.

The previous prime is 621720511. The next prime is 621720551. The reversal of 621720522 is 225027126.

621720522 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 617472801 + 4247721 = 24849^2 + 2061^2 .

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 2419018 + ... + 2419274.

Almost surely, 2^621720522 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 621720522, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (710833860).

621720522 is an abundant number, since it is smaller than the sum of its proper divisors (799947198).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

621720522 is a wasteful number, since it uses less digits than its factorization.

621720522 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 517 (or 508 counting only the distinct ones).

The product of its (nonzero) digits is 3360, while the sum is 27.

The square root of 621720522 is about 24934.3241737168. The cubic root of 621720522 is about 853.4899291809.

Adding to 621720522 its reverse (225027126), we get a palindrome (846747648).

The spelling of 621720522 in words is "six hundred twenty-one million, seven hundred twenty thousand, five hundred twenty-two".