21255205631613 has 16 divisors (see below), whose sum is σ = 28743647072256. Its totient is φ = 13968509168880.

The previous prime is 21255205631603. The next prime is 21255205631657. The reversal of 21255205631613 is 31613650255212.

It is not a de Polignac number, because 21255205631613 - 2⁶ = 21255205631549 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21255205631603) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5859445 + ... + 8766042.

It is an arithmetic number, because the mean of its divisors is an integer number (1796477942016).

Almost surely, 2^{21255205631613} is an apocalyptic number.

It is an amenable number.

21255205631613 is a deficient number, since it is larger than the sum of its proper divisors (7488441440643).

21255205631613 is a wasteful number, since it uses less digits than its factorization.

21255205631613 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14632384.

The product of its (nonzero) digits is 324000, while the sum is 42.

Adding to 21255205631613 its reverse (31613650255212), we get a palindrome (52868855886825).

The spelling of 21255205631613 in words is "twenty-one trillion, two hundred fifty-five billion, two hundred five million, six hundred thirty-one thousand, six hundred thirteen".