231640247 has 4 divisors (see below), whose sum is σ = 232085376. Its totient is φ = 231195120.

The previous prime is 231640237. The next prime is 231640261. The reversal of 231640247 is 742046132.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-231640247 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (231640207) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 221783 + ... + 222824.

It is an arithmetic number, because the mean of its divisors is an integer number (58021344).

Almost surely, 2^231640247 is an apocalyptic number.

231640247 is a deficient number, since it is larger than the sum of its proper divisors (445129).

231640247 is an equidigital number, since it uses as much as digits as its factorization.

231640247 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 445128.

The product of its (nonzero) digits is 8064, while the sum is 29.

The square root of 231640247 is about 15219.7321592727. The cubic root of 231640247 is about 614.1455930138.

Adding to 231640247 its reverse (742046132), we get a palindrome (973686379).

The spelling of 231640247 in words is "two hundred thirty-one million, six hundred forty thousand, two hundred forty-seven".