21395717 has 4 divisors (see below), whose sum is σ = 24452256. Its totient is φ = 18339180.

The previous prime is 21395677. The next prime is 21395723. The reversal of 21395717 is 71759312.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21395717 - 2⁸ = 21395461 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21395747) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1528259 + ... + 1528272.

It is an arithmetic number, because the mean of its divisors is an integer number (6113064).

Almost surely, 2^21395717 is an apocalyptic number.

It is an amenable number.

21395717 is a deficient number, since it is larger than the sum of its proper divisors (3056539).

21395717 is an equidigital number, since it uses as much as digits as its factorization.

21395717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3056538.

The product of its digits is 13230, while the sum is 35.

The square root of 21395717 is about 4625.5504537298. The cubic root of 21395717 is about 277.6145867713.

The spelling of 21395717 in words is "twenty-one million, three hundred ninety-five thousand, seven hundred seventeen".