231491639 has 2 divisors, whose sum is σ = 231491640. Its totient is φ = 231491638.

The previous prime is 231491629. The next prime is 231491677. The reversal of 231491639 is 936194132.

231491639 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an a-pointer prime, because the next prime (231491677) can be obtained adding 231491639 to its sum of digits (38).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 231491639 - 2¹⁶ = 231426103 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (231491609) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 115745819 + 115745820.

It is an arithmetic number, because the mean of its divisors is an integer number (115745820).

Almost surely, 2^231491639 is an apocalyptic number.

231491639 is a deficient number, since it is larger than the sum of its proper divisors (1).

231491639 is an equidigital number, since it uses as much as digits as its factorization.

231491639 is an evil number, because the sum of its binary digits is even.

The product of its digits is 34992, while the sum is 38.

The square root of 231491639 is about 15214.8492927140. The cubic root of 231491639 is about 614.0142305904.

The spelling of 231491639 in words is "two hundred thirty-one million, four hundred ninety-one thousand, six hundred thirty-nine".