21057727 has 2 divisors, whose sum is σ = 21057728. Its totient is φ = 21057726.

The previous prime is 21057709. The next prime is 21057731. The reversal of 21057727 is 72775012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21057727 - 2⁷ = 21057599 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21057767) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10528863 + 10528864.

It is an arithmetic number, because the mean of its divisors is an integer number (10528864).

Almost surely, 2^21057727 is an apocalyptic number.

21057727 is a deficient number, since it is larger than the sum of its proper divisors (1).

21057727 is an equidigital number, since it uses as much as digits as its factorization.

21057727 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6860, while the sum is 31.

The square root of 21057727 is about 4588.8699044536. The cubic root of 21057727 is about 276.1449870098.

The spelling of 21057727 in words is "twenty-one million, fifty-seven thousand, seven hundred twenty-seven".