21903717 has 16 divisors (see below), whose sum is σ = 32639040. Its totient is φ = 12950400.

The previous prime is 21903709. The next prime is 21903719. The reversal of 21903717 is 71730912.

21903717 is an esthetic number in base 8, because in such base its adjacent digits differ by 1.

It is not a de Polignac number, because 21903717 - 2³ = 21903709 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21903719) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6742 + ... + 9447.

It is an arithmetic number, because the mean of its divisors is an integer number (2039940).

Almost surely, 2^21903717 is an apocalyptic number.

It is an amenable number.

21903717 is a deficient number, since it is larger than the sum of its proper divisors (10735323).

21903717 is a wasteful number, since it uses less digits than its factorization.

21903717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16244.

The product of its (nonzero) digits is 2646, while the sum is 30.

The square root of 21903717 is about 4680.1407030131. The cubic root of 21903717 is about 279.7945644452.

The spelling of 21903717 in words is "twenty-one million, nine hundred three thousand, seven hundred seventeen".