21587785425 has 72 divisors (see below), whose sum is σ = 40022581248. Its totient is φ = 11111616000.

The previous prime is 21587785421. The next prime is 21587785447. The reversal of 21587785425 is 52458778512.

It is a happy number.

21587785425 is a `hidden beast` number, since 2 + 1 + 587 + 7 + 8 + 54 + 2 + 5 = 666.

It is not a de Polignac number, because 21587785425 - 2² = 21587785421 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21587785421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 2667385 + ... + 2675465.

It is an arithmetic number, because the mean of its divisors is an integer number (555869184).

Almost surely, 2^21587785425 is an apocalyptic number.

21587785425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21587785425 is a deficient number, since it is larger than the sum of its proper divisors (18434795823).

21587785425 is a wasteful number, since it uses less digits than its factorization.

21587785425 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8511 (or 8503 counting only the distinct ones).

The product of its digits is 6272000, while the sum is 54.

The spelling of 21587785425 in words is "twenty-one billion, five hundred eighty-seven million, seven hundred eighty-five thousand, four hundred twenty-five".