216728931 has 32 divisors (see below), whose sum is σ = 308095488. Its totient is φ = 135238400.

The previous prime is 216728927. The next prime is 216728933. The reversal of 216728931 is 139827612.

216728931 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 216728931 - 2² = 216728927 is a prime.

It is a super-2 number, since 2×216728931² = 93942859064805522, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 216728931.

It is not an unprimeable number, because it can be changed into a prime (216728933) 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, 954640 + ... + 954866.

It is an arithmetic number, because the mean of its divisors is an integer number (9627984).

Almost surely, 2^216728931 is an apocalyptic number.

216728931 is a deficient number, since it is larger than the sum of its proper divisors (91366557).

216728931 is a wasteful number, since it uses less digits than its factorization.

216728931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 491.

The product of its digits is 36288, while the sum is 39.

The square root of 216728931 is about 14721.7163061920. The cubic root of 216728931 is about 600.6741783001.

It can be divided in two parts, 21672 and 8931, that added together give a palindrome (30603).

The spelling of 216728931 in words is "two hundred sixteen million, seven hundred twenty-eight thousand, nine hundred thirty-one".