21207686625 has 64 divisors (see below), whose sum is σ = 40045224960. Its totient is φ = 11070028800.

The previous prime is 21207686623. The next prime is 21207686629. The reversal of 21207686625 is 52668670212.

21207686625 is a `hidden beast` number, since 2 + 12 + 0 + 7 + 6 + 8 + 6 + 625 = 666.

It is not a de Polignac number, because 21207686625 - 2¹ = 21207686623 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21207686623) by changing a digit.

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 63 ways as a sum of consecutive naturals, for example, 91777 + ... + 225473.

It is an arithmetic number, because the mean of its divisors is an integer number (625706640).

Almost surely, 2^21207686625 is an apocalyptic number.

21207686625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21207686625 is a deficient number, since it is larger than the sum of its proper divisors (18837538335).

21207686625 is a wasteful number, since it uses less digits than its factorization.

21207686625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 133768 (or 133752 counting only the distinct ones).

The product of its (nonzero) digits is 483840, while the sum is 45.

The spelling of 21207686625 in words is "twenty-one billion, two hundred seven million, six hundred eighty-six thousand, six hundred twenty-five".