256621003523321 has 4 divisors (see below), whose sum is σ = 256621706272932. Its totient is φ = 256620300773712.

The previous prime is 256621003523309. The next prime is 256621003523359. The reversal of 256621003523321 is 123325300126652.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 17588964966400 + 239032038556921 = 4193920^2 + 15460661^2 .

It is a cyclic number.

It is not a de Polignac number, because 256621003523321 - 2³⁸ = 256346125616377 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (256621003523821) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 350826770 + ... + 351557483.

It is an arithmetic number, because the mean of its divisors is an integer number (64155426568233).

Almost surely, 2^{256621003523321} is an apocalyptic number.

It is an amenable number.

256621003523321 is a deficient number, since it is larger than the sum of its proper divisors (702749611).

256621003523321 is an equidigital number, since it uses as much as digits as its factorization.

256621003523321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 702749610.

The product of its (nonzero) digits is 388800, while the sum is 41.

Adding to 256621003523321 its reverse (123325300126652), we get a palindrome (379946303649973).

The spelling of 256621003523321 in words is "two hundred fifty-six trillion, six hundred twenty-one billion, three million, five hundred twenty-three thousand, three hundred twenty-one".