21979125 has 48 divisors (see below), whose sum is σ = 45297408. Its totient is φ = 10044000.

The previous prime is 21979121. The next prime is 21979151. The reversal of 21979125 is 52197912.

It is not a de Polignac number, because 21979125 - 2² = 21979121 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21979125.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21979121) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 6480 + ... + 9270.

It is an arithmetic number, because the mean of its divisors is an integer number (943696).

Almost surely, 2^21979125 is an apocalyptic number.

21979125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21979125 is an abundant number, since it is smaller than the sum of its proper divisors (23318283).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21979125 is a wasteful number, since it uses less digits than its factorization.

21979125 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2819 (or 2806 counting only the distinct ones).

The product of its digits is 11340, while the sum is 36.

The square root of 21979125 is about 4688.1899492235. The cubic root of 21979125 is about 280.1152799121.

The spelling of 21979125 in words is "twenty-one million, nine hundred seventy-nine thousand, one hundred twenty-five".