21504320725 has 6 divisors (see below), whose sum is σ = 26665357730. Its totient is φ = 17203456560.

The previous prime is 21504320701. The next prime is 21504320759. The reversal of 21504320725 is 52702340512.

It can be written as a sum of positive squares in 3 ways, for example, as 307581444 + 21196739281 = 17538^2 + 145591^2 .

It is not a de Polignac number, because 21504320725 - 2¹⁹ = 21503796437 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 430086390 + ... + 430086439.

Almost surely, 2^21504320725 is an apocalyptic number.

21504320725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21504320725 is a deficient number, since it is larger than the sum of its proper divisors (5161037005).

21504320725 is an equidigital number, since it uses as much as digits as its factorization.

21504320725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 860172839 (or 860172834 counting only the distinct ones).

The product of its (nonzero) digits is 16800, while the sum is 31.

The spelling of 21504320725 in words is "twenty-one billion, five hundred four million, three hundred twenty thousand, seven hundred twenty-five".