21366561025 has 24 divisors (see below), whose sum is σ = 26888390144. Its totient is φ = 16840742400.

The previous prime is 21366561019. The next prime is 21366561049. The reversal of 21366561025 is 52016566312.

It is not a de Polignac number, because 21366561025 - 2⁹ = 21366560513 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 521020 + ... + 560530.

Almost surely, 2^21366561025 is an apocalyptic number.

21366561025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21366561025 is a deficient number, since it is larger than the sum of its proper divisors (5521829119).

21366561025 is a wasteful number, since it uses less digits than its factorization.

21366561025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39841 (or 39836 counting only the distinct ones).

The product of its (nonzero) digits is 64800, while the sum is 37.

The spelling of 21366561025 in words is "twenty-one billion, three hundred sixty-six million, five hundred sixty-one thousand, twenty-five".