8399721231 has 24 divisors (see below), whose sum is σ = 13517547264. Its totient is φ = 4982423760.

The previous prime is 8399721163. The next prime is 8399721247. The reversal of 8399721231 is 1321279938.

8399721231 is a `hidden beast` number, since 8 + 399 + 7 + 21 + 231 = 666.

It is not a de Polignac number, because 8399721231 - 2²² = 8395526927 is a prime.

It is a super-2 number, since 2×8399721231² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8399721251) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 897961 + ... + 907266.

It is an arithmetic number, because the mean of its divisors is an integer number (563231136).

Almost surely, 2^8399721231 is an apocalyptic number.

8399721231 is a deficient number, since it is larger than the sum of its proper divisors (5117826033).

8399721231 is a wasteful number, since it uses less digits than its factorization.

8399721231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1805291 (or 1805288 counting only the distinct ones).

The product of its digits is 163296, while the sum is 45.

The square root of 8399721231 is about 91649.9930769228. The cubic root of 8399721231 is about 2032.7702260955.

The spelling of 8399721231 in words is "eight billion, three hundred ninety-nine million, seven hundred twenty-one thousand, two hundred thirty-one".