21395723 has 2 divisors, whose sum is σ = 21395724. Its totient is φ = 21395722.

The previous prime is 21395677. The next prime is 21395747. The reversal of 21395723 is 32759312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21395723 - 2⁶ = 21395659 is a prime.

It is a Sophie Germain prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21395723.

It is not a weakly prime, because it can be changed into another prime (21395783) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10697861 + 10697862.

It is an arithmetic number, because the mean of its divisors is an integer number (10697862).

Almost surely, 2^21395723 is an apocalyptic number.

21395723 is a deficient number, since it is larger than the sum of its proper divisors (1).

21395723 is an equidigital number, since it uses as much as digits as its factorization.

21395723 is an evil number, because the sum of its binary digits is even.

The product of its digits is 11340, while the sum is 32.

The square root of 21395723 is about 4625.5511023012. The cubic root of 21395723 is about 277.6146127217.

The spelling of 21395723 in words is "twenty-one million, three hundred ninety-five thousand, seven hundred twenty-three".