621591664 has 40 divisors (see below), whose sum is σ = 1257240960. Its totient is φ = 297369600.

The previous prime is 621591653. The next prime is 621591667. The reversal of 621591664 is 466195126.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (621591667) 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 7 ways as a sum of consecutive naturals, for example, 37104 + ... + 51184.

It is an arithmetic number, because the mean of its divisors is an integer number (31431024).

Almost surely, 2^621591664 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 621591664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (628620480).

621591664 is an abundant number, since it is smaller than the sum of its proper divisors (635649296).

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

621591664 is a wasteful number, since it uses less digits than its factorization.

621591664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14209 (or 14203 counting only the distinct ones).

The product of its digits is 77760, while the sum is 40.

The square root of 621591664 is about 24931.7400916984. The cubic root of 621591664 is about 853.4309602388.

It can be divided in two parts, 6215 and 91664, that added together give a palindrome (97879).

The spelling of 621591664 in words is "six hundred twenty-one million, five hundred ninety-one thousand, six hundred sixty-four".