21205606625 has 64 divisors (see below), whose sum is σ = 32078052864. Its totient is φ = 13662720000.

The previous prime is 21205606607. The next prime is 21205606651. The reversal of 21205606625 is 52660650212.

It is not a de Polignac number, because 21205606625 - 2⁶ = 21205606561 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 17656025 + ... + 17657225.

It is an arithmetic number, because the mean of its divisors is an integer number (501219576).

Almost surely, 2^21205606625 is an apocalyptic number.

21205606625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21205606625 is a deficient number, since it is larger than the sum of its proper divisors (10872446239).

21205606625 is a wasteful number, since it uses less digits than its factorization.

21205606625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2427 (or 2417 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 35.

The spelling of 21205606625 in words is "twenty-one billion, two hundred five million, six hundred six thousand, six hundred twenty-five".