21990825 has 24 divisors (see below), whose sum is σ = 40399200. Its totient is φ = 11728080.

The previous prime is 21990823. The next prime is 21990851. The reversal of 21990825 is 52809912.

It is not a de Polignac number, because 21990825 - 2¹ = 21990823 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21990825.

It is not an unprimeable number, because it can be changed into a prime (21990821) 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, 15615 + ... + 16964.

It is an arithmetic number, because the mean of its divisors is an integer number (1683300).

Almost surely, 2^21990825 is an apocalyptic number.

21990825 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21990825 is a deficient number, since it is larger than the sum of its proper divisors (18408375).

21990825 is a wasteful number, since it uses less digits than its factorization.

21990825 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32598 (or 32587 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 36.

The square root of 21990825 is about 4689.4375995422. The cubic root of 21990825 is about 280.1649750571.

The spelling of 21990825 in words is "twenty-one million, nine hundred ninety thousand, eight hundred twenty-five".