21019727 has 2 divisors, whose sum is σ = 21019728. Its totient is φ = 21019726.

The previous prime is 21019699. The next prime is 21019729. The reversal of 21019727 is 72791012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21019727 - 2¹⁴ = 21003343 is a prime.

Together with 21019729, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21019727.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21019729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10509863 + 10509864.

It is an arithmetic number, because the mean of its divisors is an integer number (10509864).

Almost surely, 2^21019727 is an apocalyptic number.

21019727 is a deficient number, since it is larger than the sum of its proper divisors (1).

21019727 is an equidigital number, since it uses as much as digits as its factorization.

21019727 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1764, while the sum is 29.

The square root of 21019727 is about 4584.7275818744. The cubic root of 21019727 is about 275.9787799621.

The spelling of 21019727 in words is "twenty-one million, nineteen thousand, seven hundred twenty-seven".