21697927 has 2 divisors, whose sum is σ = 21697928. Its totient is φ = 21697926.

The previous prime is 21697913. The next prime is 21697937. The reversal of 21697927 is 72979612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21697927 - 2¹¹ = 21695879 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21697937) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10848963 + 10848964.

It is an arithmetic number, because the mean of its divisors is an integer number (10848964).

Almost surely, 2^21697927 is an apocalyptic number.

21697927 is a deficient number, since it is larger than the sum of its proper divisors (1).

21697927 is an equidigital number, since it uses as much as digits as its factorization.

21697927 is an evil number, because the sum of its binary digits is even.

The product of its digits is 95256, while the sum is 43.

The square root of 21697927 is about 4658.1033693983. The cubic root of 21697927 is about 278.9155630629.

The spelling of 21697927 in words is "twenty-one million, six hundred ninety-seven thousand, nine hundred twenty-seven".