20921810625 has 80 divisors (see below), whose sum is σ = 39110980480. Its totient is φ = 11049048000.

The previous prime is 20921810599. The next prime is 20921810719. The reversal of 20921810625 is 52601812902.

20921810625 is a `hidden beast` number, since 2 + 0 + 9 + 2 + 18 + 10 + 625 = 666.

It is not a de Polignac number, because 20921810625 - 2⁹ = 20921810113 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 20921810625.

It is an unprimeable number.

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 79 ways as a sum of consecutive naturals, for example, 1732107 + ... + 1744143.

It is an arithmetic number, because the mean of its divisors is an integer number (488887256).

Almost surely, 2^20921810625 is an apocalyptic number.

20921810625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

20921810625 is a deficient number, since it is larger than the sum of its proper divisors (18189169855).

20921810625 is a wasteful number, since it uses less digits than its factorization.

20921810625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12169 (or 12148 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The spelling of 20921810625 in words is "twenty billion, nine hundred twenty-one million, eight hundred ten thousand, six hundred twenty-five".