857640239 has 2 divisors, whose sum is σ = 857640240. Its totient is φ = 857640238.

The previous prime is 857640197. The next prime is 857640253. The reversal of 857640239 is 932046758.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 857640239 - 2²⁸ = 589204783 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 857640239.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (857640269) 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 as a sum of consecutive naturals, namely, 428820119 + 428820120.

It is an arithmetic number, because the mean of its divisors is an integer number (428820120).

Almost surely, 2^857640239 is an apocalyptic number.

857640239 is a deficient number, since it is larger than the sum of its proper divisors (1).

857640239 is an equidigital number, since it uses as much as digits as its factorization.

857640239 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 362880, while the sum is 44.

The square root of 857640239 is about 29285.4953688682. The cubic root of 857640239 is about 950.0979544425.

The spelling of 857640239 in words is "eight hundred fifty-seven million, six hundred forty thousand, two hundred thirty-nine".