21405332925 has 72 divisors (see below), whose sum is σ = 38766043368. Its totient is φ = 11289600000.

The previous prime is 21405332903. The next prime is 21405332989. The reversal of 21405332925 is 52923350412.

It can be written as a sum of positive squares in 12 ways, for example, as 15737953401 + 5667379524 = 125451^2 + 75282^2 .

It is not a de Polignac number, because 21405332925 - 2¹⁵ = 21405300157 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21405332925.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 17822325 + ... + 17823525.

It is an arithmetic number, because the mean of its divisors is an integer number (538417269).

Almost surely, 2^21405332925 is an apocalyptic number.

21405332925 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21405332925 is a deficient number, since it is larger than the sum of its proper divisors (17360710443).

21405332925 is a wasteful number, since it uses less digits than its factorization.

21405332925 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2031 (or 2023 counting only the distinct ones).

The product of its (nonzero) digits is 64800, while the sum is 36.

The spelling of 21405332925 in words is "twenty-one billion, four hundred five million, three hundred thirty-two thousand, nine hundred twenty-five".