231078721 has 4 divisors (see below), whose sum is σ = 231118272. Its totient is φ = 231039172.

The previous prime is 231078709. The next prime is 231078733. The reversal of 231078721 is 127870132.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (231078709) and next prime (231078733).

It is a cyclic number.

It is not a de Polignac number, because 231078721 - 2¹³ = 231070529 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (231078761) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9085 + ... + 23338.

It is an arithmetic number, because the mean of its divisors is an integer number (57779568).

Almost surely, 2^231078721 is an apocalyptic number.

It is an amenable number.

231078721 is a deficient number, since it is larger than the sum of its proper divisors (39551).

231078721 is an equidigital number, since it uses as much as digits as its factorization.

231078721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39550.

The product of its (nonzero) digits is 4704, while the sum is 31.

The square root of 231078721 is about 15201.2736637428. The cubic root of 231078721 is about 613.6489352879.

The spelling of 231078721 in words is "two hundred thirty-one million, seventy-eight thousand, seven hundred twenty-one".