256621343220 has 72 divisors (see below), whose sum is σ = 849183360480. Its totient is φ = 62211234240.

The previous prime is 256621343201. The next prime is 256621343221. The reversal of 256621343220 is 22343126652.

256621343220 is a `hidden beast` number, since 2 + 5 + 6 + 6 + 213 + 432 + 2 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256621343221) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 64801390 + ... + 64805349.

It is an arithmetic number, because the mean of its divisors is an integer number (11794213340).

Almost surely, 2^256621343220 is an apocalyptic number.

256621343220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

256621343220 is an abundant number, since it is smaller than the sum of its proper divisors (592562017260).

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

256621343220 is a wasteful number, since it uses less digits than its factorization.

256621343220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129606765 (or 129606760 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 36.

Adding to 256621343220 its reverse (22343126652), we get a palindrome (278964469872).

The spelling of 256621343220 in words is "two hundred fifty-six billion, six hundred twenty-one million, three hundred forty-three thousand, two hundred twenty".