21521445031451 has 4 divisors (see below), whose sum is σ = 21665884260000. Its totient is φ = 21377005802904.

The previous prime is 21521445031403. The next prime is 21521445031523. The reversal of 21521445031451 is 15413054412512.

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 21521445031451 - 2³⁸ = 21246567124507 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21521445030451) 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, 72219614051 + ... + 72219614348.

It is an arithmetic number, because the mean of its divisors is an integer number (5416471065000).

Almost surely, 2^{21521445031451} is an apocalyptic number.

21521445031451 is a deficient number, since it is larger than the sum of its proper divisors (144439228549).

21521445031451 is a wasteful number, since it uses less digits than its factorization.

21521445031451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 144439228548.

The product of its (nonzero) digits is 96000, while the sum is 38.

Adding to 21521445031451 its reverse (15413054412512), we get a palindrome (36934499443963).

The spelling of 21521445031451 in words is "twenty-one trillion, five hundred twenty-one billion, four hundred forty-five million, thirty-one thousand, four hundred fifty-one".