231432721 has 8 divisors (see below), whose sum is σ = 249467904. Its totient is φ = 213430800.

The previous prime is 231432709. The next prime is 231432727. The reversal of 231432721 is 127234132.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-231432721 is a prime.

It is a super-2 number, since 2×231432721² = 107122208698927682, which contains 22 as substring.

It is a Duffinian number.

It is a nialpdrome in base 16.

It is not an unprimeable number, because it can be changed into a prime (231432727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7230 + ... + 22696.

It is an arithmetic number, because the mean of its divisors is an integer number (31183488).

Almost surely, 2^231432721 is an apocalyptic number.

It is an amenable number.

231432721 is a deficient number, since it is larger than the sum of its proper divisors (18035183).

231432721 is a wasteful number, since it uses less digits than its factorization.

231432721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16631.

The product of its digits is 2016, while the sum is 25.

The square root of 231432721 is about 15212.9129689222. The cubic root of 231432721 is about 613.9621343100.

Adding to 231432721 its reverse (127234132), we get a palindrome (358666853).

The spelling of 231432721 in words is "two hundred thirty-one million, four hundred thirty-two thousand, seven hundred twenty-one".