621656 has 32 divisors (see below), whose sum is σ = 1412640. Its totient is φ = 250368.

The previous prime is 621641. The next prime is 621671. The reversal of 621656 is 656126.

621656 = 295² + 296² + ... + 301².

621656 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (621641) and next prime (621671).

It is a plaindrome in base 9.

It is a congruent number.

It is an unprimeable number.

621656 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 626 + ... + 1278.

It is an arithmetic number, because the mean of its divisors is an integer number (44145).

2⁶²¹⁶⁵⁶ 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 621656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (706320).

621656 is an abundant number, since it is smaller than the sum of its proper divisors (790984).

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

621656 is a wasteful number, since it uses less digits than its factorization.

621656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 683 (or 679 counting only the distinct ones).

The product of its digits is 2160, while the sum is 26.

The square root of 621656 is about 788.4516472175. The cubic root of 621656 is about 85.3460403169.

The spelling of 621656 in words is "six hundred twenty-one thousand, six hundred fifty-six".