688400239 has 2 divisors, whose sum is σ = 688400240. Its totient is φ = 688400238.

The previous prime is 688400213. The next prime is 688400243. The reversal of 688400239 is 932004886.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 688400239 - 2²¹ = 686303087 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 (688400249) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 344200119 + 344200120.

It is an arithmetic number, because the mean of its divisors is an integer number (344200120).

Almost surely, 2^688400239 is an apocalyptic number.

688400239 is a deficient number, since it is larger than the sum of its proper divisors (1).

688400239 is an equidigital number, since it uses as much as digits as its factorization.

688400239 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 82944, while the sum is 40.

The square root of 688400239 is about 26237.3824723428. The cubic root of 688400239 is about 882.9721469906.

The spelling of 688400239 in words is "six hundred eighty-eight million, four hundred thousand, two hundred thirty-nine".