21821277255625 has 45 divisors (see below), whose sum is σ = 27746629827697. Its totient is φ = 17155721342000.

The previous prime is 21821277255619. The next prime is 21821277255649. The reversal of 21821277255625 is 52655277212812.

The square root of 21821277255625 is 4671325.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 2 ways, for example, as 1710788136841 + 20110489118784 = 1307971^2 + 4484472^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21821277255625 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 6890202792 + ... + 6890205958.

Almost surely, 2^{21821277255625} is an apocalyptic number.

21821277255625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21821277255625 is the 4671325-th square number.

21821277255625 is the 2335663-rd centered octagonal number.

It is an amenable number.

21821277255625 is a deficient number, since it is larger than the sum of its proper divisors (5925352572072).

21821277255625 is an frugal number, since it uses more digits than its factorization.

21821277255625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6472 (or 3231 counting only the distinct ones).

The product of its digits is 9408000, while the sum is 55.

The spelling of 21821277255625 in words is "twenty-one trillion, eight hundred twenty-one billion, two hundred seventy-seven million, two hundred fifty-five thousand, six hundred twenty-five".