21539501025 has 24 divisors (see below), whose sum is σ = 40699401024. Its totient is φ = 9846628800.

The previous prime is 21539501023. The next prime is 21539501029. The reversal of 21539501025 is 52010593512.

It is not a de Polignac number, because 21539501025 - 2¹ = 21539501023 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21539501023) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 20513286 + ... + 20514335.

It is an arithmetic number, because the mean of its divisors is an integer number (1695808376).

Almost surely, 2^21539501025 is an apocalyptic number.

21539501025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21539501025 is a deficient number, since it is larger than the sum of its proper divisors (19159899999).

21539501025 is a wasteful number, since it uses less digits than its factorization.

21539501025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41027641 (or 41027636 counting only the distinct ones).

The product of its (nonzero) digits is 13500, while the sum is 33.

The spelling of 21539501025 in words is "twenty-one billion, five hundred thirty-nine million, five hundred one thousand, twenty-five".