21365716 has 6 divisors (see below), whose sum is σ = 37390010. Its totient is φ = 10682856.

The previous prime is 21365699. The next prime is 21365723. The reversal of 21365716 is 61756312.

It can be written as a sum of positive squares in only one way, i.e., 21344400 + 21316 = 4620^2 + 146^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2670711 + ... + 2670718.

Almost surely, 2^21365716 is an apocalyptic number.

It is an amenable number.

21365716 is a deficient number, since it is larger than the sum of its proper divisors (16024294).

21365716 is a wasteful number, since it uses less digits than its factorization.

21365716 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5341433 (or 5341431 counting only the distinct ones).

The product of its digits is 7560, while the sum is 31.

The square root of 21365716 is about 4622.3063507301. The cubic root of 21365716 is about 277.4847693397.

The spelling of 21365716 in words is "twenty-one million, three hundred sixty-five thousand, seven hundred sixteen".