21251302002551 has 4 divisors (see below), whose sum is σ = 21320524484952. Its totient is φ = 21182079520152.

The previous prime is 21251302002527. The next prime is 21251302002583. The reversal of 21251302002551 is 15520020315212.

It is a happy number.

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 21251302002551 - 2²⁶ = 21251234893687 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21251302002751) 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, 34611240740 + ... + 34611241353.

It is an arithmetic number, because the mean of its divisors is an integer number (5330131121238).

Almost surely, 2^{21251302002551} is an apocalyptic number.

21251302002551 is a deficient number, since it is larger than the sum of its proper divisors (69222482401).

21251302002551 is an equidigital number, since it uses as much as digits as its factorization.

21251302002551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69222482400.

The product of its (nonzero) digits is 6000, while the sum is 29.

Adding to 21251302002551 its reverse (15520020315212), we get a palindrome (36771322317763).

The spelling of 21251302002551 in words is "twenty-one trillion, two hundred fifty-one billion, three hundred two million, two thousand, five hundred fifty-one".