21502316465251 has 4 divisors (see below), whose sum is σ = 21514724035632. Its totient is φ = 21489908894872.

The previous prime is 21502316465233. The next prime is 21502316465261. The reversal of 21502316465251 is 15256461320512.

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

It is a cyclic number.

It is not a de Polignac number, because 21502316465251 - 2²¹ = 21502314368099 is a prime.

It is a super-2 number, since 2×21502316465251² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21502316465198 and 21502316465207.

It is not an unprimeable number, because it can be changed into a prime (21502316465261) 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, 6203782591 + ... + 6203786056.

It is an arithmetic number, because the mean of its divisors is an integer number (5378681008908).

Almost surely, 2^{21502316465251} is an apocalyptic number.

21502316465251 is a deficient number, since it is larger than the sum of its proper divisors (12407570381).

21502316465251 is a wasteful number, since it uses less digits than its factorization.

21502316465251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12407570380.

The product of its (nonzero) digits is 432000, while the sum is 43.

Adding to 21502316465251 its reverse (15256461320512), we get a palindrome (36758777785763).

The spelling of 21502316465251 in words is "twenty-one trillion, five hundred two billion, three hundred sixteen million, four hundred sixty-five thousand, two hundred fifty-one".