21316731 has 8 divisors (see below), whose sum is σ = 28509504. Its totient is φ = 14167560.

The previous prime is 21316723. The next prime is 21316739. The reversal of 21316731 is 13761312.

It is an interprime number because it is at equal distance from previous prime (21316723) and next prime (21316739).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21316731 - 2³ = 21316723 is a prime.

It is a super-2 number, since 2×21316731² = 908806041052722, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21316739) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9741 + ... + 11726.

It is an arithmetic number, because the mean of its divisors is an integer number (3563688).

Almost surely, 2^21316731 is an apocalyptic number.

21316731 is a deficient number, since it is larger than the sum of its proper divisors (7192773).

21316731 is a wasteful number, since it uses less digits than its factorization.

21316731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21801.

The product of its digits is 756, while the sum is 24.

The square root of 21316731 is about 4617.0045484058. The cubic root of 21316731 is about 277.2725447247.

The spelling of 21316731 in words is "twenty-one million, three hundred sixteen thousand, seven hundred thirty-one".