21709927 has 2 divisors, whose sum is σ = 21709928. Its totient is φ = 21709926.

The previous prime is 21709921. The next prime is 21709931. The reversal of 21709927 is 72990712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21709927 - 2¹⁹ = 21185639 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21709921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10854963 + 10854964.

It is an arithmetic number, because the mean of its divisors is an integer number (10854964).

Almost surely, 2^21709927 is an apocalyptic number.

21709927 is a deficient number, since it is larger than the sum of its proper divisors (1).

21709927 is an equidigital number, since it uses as much as digits as its factorization.

21709927 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 15876, while the sum is 37.

The square root of 21709927 is about 4659.3912692540. The cubic root of 21709927 is about 278.9669715059.

The spelling of 21709927 in words is "twenty-one million, seven hundred nine thousand, nine hundred twenty-seven".