21451299557 has 2 divisors, whose sum is σ = 21451299558. Its totient is φ = 21451299556.

The previous prime is 21451299539. The next prime is 21451299613. The reversal of 21451299557 is 75599215412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18365941441 + 3085358116 = 135521^2 + 55546^2 .

It is a cyclic number.

It is not a de Polignac number, because 21451299557 - 2²⁴ = 21434522341 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21451299757) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10725649778 + 10725649779.

It is an arithmetic number, because the mean of its divisors is an integer number (10725649779).

Almost surely, 2^21451299557 is an apocalyptic number.

It is an amenable number.

21451299557 is a deficient number, since it is larger than the sum of its proper divisors (1).

21451299557 is an equidigital number, since it uses as much as digits as its factorization.

21451299557 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1134000, while the sum is 50.

The spelling of 21451299557 in words is "twenty-one billion, four hundred fifty-one million, two hundred ninety-nine thousand, five hundred fifty-seven".