21791625 has 16 divisors (see below), whose sum is σ = 36261888. Its totient is φ = 11622000.

The previous prime is 21791617. The next prime is 21791629. The reversal of 21791625 is 52619712.

It is not a de Polignac number, because 21791625 - 2³ = 21791617 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21791629) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 28681 + ... + 29430.

It is an arithmetic number, because the mean of its divisors is an integer number (2266368).

Almost surely, 2^21791625 is an apocalyptic number.

21791625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21791625 is a deficient number, since it is larger than the sum of its proper divisors (14470263).

21791625 is an equidigital number, since it uses as much as digits as its factorization.

21791625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58129 (or 58119 counting only the distinct ones).

The product of its digits is 7560, while the sum is 33.

The square root of 21791625 is about 4668.1500618553. The cubic root of 21791625 is about 279.3164662240.

The spelling of 21791625 in words is "twenty-one million, seven hundred ninety-one thousand, six hundred twenty-five".