816721731 has 32 divisors (see below), whose sum is σ = 1384358400. Its totient is φ = 466175520.

The previous prime is 816721729. The next prime is 816721739. The reversal of 816721731 is 137127618.

816721731 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 816721731 - 2¹ = 816721729 is a prime.

It is a super-2 number, since 2×816721731² = 1334068771775272722, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (816721739) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 221380 + ... + 225038.

It is an arithmetic number, because the mean of its divisors is an integer number (43261200).

Almost surely, 2^816721731 is an apocalyptic number.

816721731 is a deficient number, since it is larger than the sum of its proper divisors (567636669).

816721731 is a wasteful number, since it uses less digits than its factorization.

816721731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4856 (or 4850 counting only the distinct ones).

The product of its digits is 14112, while the sum is 36.

The square root of 816721731 is about 28578.3437413717. The cubic root of 816721731 is about 934.7411681201.

The spelling of 816721731 in words is "eight hundred sixteen million, seven hundred twenty-one thousand, seven hundred thirty-one".