21975187 has 12 divisors (see below), whose sum is σ = 24467520. Its totient is φ = 19619280.

The previous prime is 21975167. The next prime is 21975287. The reversal of 21975187 is 78157912.

It is not a de Polignac number, because 21975187 - 2¹⁹ = 21450899 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21975137) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11614 + ... + 13372.

It is an arithmetic number, because the mean of its divisors is an integer number (2038960).

Almost surely, 2^21975187 is an apocalyptic number.

21975187 is a deficient number, since it is larger than the sum of its proper divisors (2492333).

21975187 is a wasteful number, since it uses less digits than its factorization.

21975187 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1834 (or 1803 counting only the distinct ones).

The product of its digits is 35280, while the sum is 40.

The square root of 21975187 is about 4687.7699388942. The cubic root of 21975187 is about 280.0985494939.

The spelling of 21975187 in words is "twenty-one million, nine hundred seventy-five thousand, one hundred eighty-seven".