21302415251 has 16 divisors (see below), whose sum is σ = 23167317600. Its totient is φ = 19470025728.

The previous prime is 21302415227. The next prime is 21302415257. The reversal of 21302415251 is 15251420312.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21302415251 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21302415251.

It is not an unprimeable number, because it can be changed into a prime (21302415257) 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, 5157155 + ... + 5161283.

It is an arithmetic number, because the mean of its divisors is an integer number (1447957350).

Almost surely, 2^21302415251 is an apocalyptic number.

21302415251 is a deficient number, since it is larger than the sum of its proper divisors (1864902349).

21302415251 is a wasteful number, since it uses less digits than its factorization.

21302415251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7958.

The product of its (nonzero) digits is 2400, while the sum is 26.

Adding to 21302415251 its reverse (15251420312), we get a palindrome (36553835563).

The spelling of 21302415251 in words is "twenty-one billion, three hundred two million, four hundred fifteen thousand, two hundred fifty-one".