21878025 has 48 divisors (see below), whose sum is σ = 41039040. Its totient is φ = 10195200.

The previous prime is 21877951. The next prime is 21878047. The reversal of 21878025 is 52087812.

It is not a de Polignac number, because 21878025 - 2⁷ = 21877897 is a prime.

It is a hoax number, since the sum of its digits (33) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 17935 + ... + 19115.

It is an arithmetic number, because the mean of its divisors is an integer number (854980).

Almost surely, 2^21878025 is an apocalyptic number.

21878025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21878025 is a deficient number, since it is larger than the sum of its proper divisors (19161015).

21878025 is a wasteful number, since it uses less digits than its factorization.

21878025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1226 (or 1221 counting only the distinct ones).

The product of its (nonzero) digits is 8960, while the sum is 33.

The square root of 21878025 is about 4677.3951083910. The cubic root of 21878025 is about 279.6851264844.

The spelling of 21878025 in words is "twenty-one million, eight hundred seventy-eight thousand, twenty-five".