21716915 has 16 divisors (see below), whose sum is σ = 28899936. Its totient is φ = 15532800.

The previous prime is 21716887. The next prime is 21716927. The reversal of 21716915 is 51961712.

It is not a de Polignac number, because 21716915 - 2⁸ = 21716659 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 119 + ... + 6591.

It is an arithmetic number, because the mean of its divisors is an integer number (1806246).

Almost surely, 2^21716915 is an apocalyptic number.

21716915 is a deficient number, since it is larger than the sum of its proper divisors (7183021).

21716915 is a wasteful number, since it uses less digits than its factorization.

21716915 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6550.

The product of its digits is 3780, while the sum is 32.

The square root of 21716915 is about 4660.1410922847. The cubic root of 21716915 is about 278.9968996285.

The spelling of 21716915 in words is "twenty-one million, seven hundred sixteen thousand, nine hundred fifteen".