21985927 has 2 divisors, whose sum is σ = 21985928. Its totient is φ = 21985926.

The previous prime is 21985903. The next prime is 21985939. The reversal of 21985927 is 72958912.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21985927 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21985027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10992963 + 10992964.

It is an arithmetic number, because the mean of its divisors is an integer number (10992964).

Almost surely, 2^21985927 is an apocalyptic number.

21985927 is a deficient number, since it is larger than the sum of its proper divisors (1).

21985927 is an equidigital number, since it uses as much as digits as its factorization.

21985927 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 90720, while the sum is 43.

The square root of 21985927 is about 4688.9153329955. The cubic root of 21985927 is about 280.1441732008.

The spelling of 21985927 in words is "twenty-one million, nine hundred eighty-five thousand, nine hundred twenty-seven".