21945825 has 36 divisors (see below), whose sum is σ = 42885648. Its totient is φ = 10639200.

The previous prime is 21945823. The next prime is 21945829. The reversal of 21945825 is 52854912.

It is not a de Polignac number, because 21945825 - 2¹ = 21945823 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21945825.

It is not an unprimeable number, because it can be changed into a prime (21945821) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 1959 + ... + 6908.

It is an arithmetic number, because the mean of its divisors is an integer number (1191268).

Almost surely, 2^21945825 is an apocalyptic number.

21945825 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21945825 is a deficient number, since it is larger than the sum of its proper divisors (20939823).

21945825 is a wasteful number, since it uses less digits than its factorization.

21945825 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8894 (or 8886 counting only the distinct ones).

The product of its digits is 28800, while the sum is 36.

The square root of 21945825 is about 4684.6371257548. The cubic root of 21945825 is about 279.9737432862.

The spelling of 21945825 in words is "twenty-one million, nine hundred forty-five thousand, eight hundred twenty-five".