231630721 has 4 divisors (see below), whose sum is σ = 264720832. Its totient is φ = 198540612.

The previous prime is 231630713. The next prime is 231630727. The reversal of 231630721 is 127036132.

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 a cyclic number.

It is not a de Polignac number, because 231630721 - 2³ = 231630713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (231630727) 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, 16545045 + ... + 16545058.

It is an arithmetic number, because the mean of its divisors is an integer number (66180208).

Almost surely, 2^231630721 is an apocalyptic number.

It is an amenable number.

231630721 is a deficient number, since it is larger than the sum of its proper divisors (33090111).

231630721 is an equidigital number, since it uses as much as digits as its factorization.

231630721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33090110.

The product of its (nonzero) digits is 1512, while the sum is 25.

The square root of 231630721 is about 15219.4192070525. The cubic root of 231630721 is about 614.1371741672.

Adding to 231630721 its reverse (127036132), we get a palindrome (358666853).

The spelling of 231630721 in words is "two hundred thirty-one million, six hundred thirty thousand, seven hundred twenty-one".