21791825 has 24 divisors (see below), whose sum is σ = 29789760. Its totient is φ = 15681600.

The previous prime is 21791821. The next prime is 21791837. The reversal of 21791825 is 52819712.

It is not a de Polignac number, because 21791825 - 2² = 21791821 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21791821) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 29612 + ... + 30338.

It is an arithmetic number, because the mean of its divisors is an integer number (1241240).

Almost surely, 2^21791825 is an apocalyptic number.

21791825 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21791825 is a deficient number, since it is larger than the sum of its proper divisors (7997935).

21791825 is a wasteful number, since it uses less digits than its factorization.

21791825 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 857 (or 852 counting only the distinct ones).

The product of its digits is 10080, while the sum is 35.

The square root of 21791825 is about 4668.1714835683. The cubic root of 21791825 is about 279.3173207285.

It can be divided in two parts, 2179 and 1825, that added together give a palindrome (4004).

The spelling of 21791825 in words is "twenty-one million, seven hundred ninety-one thousand, eight hundred twenty-five".