688137979 has 2 divisors, whose sum is σ = 688137980. Its totient is φ = 688137978.

The previous prime is 688137971. The next prime is 688137997. The reversal of 688137979 is 979731886.

Together with next prime (688137997) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 688137979 - 2³ = 688137971 is a prime.

It is not a weakly prime, because it can be changed into another prime (688137971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 344068989 + 344068990.

It is an arithmetic number, because the mean of its divisors is an integer number (344068990).

Almost surely, 2^688137979 is an apocalyptic number.

688137979 is a deficient number, since it is larger than the sum of its proper divisors (1).

688137979 is an equidigital number, since it uses as much as digits as its factorization.

688137979 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4572288, while the sum is 58.

The square root of 688137979 is about 26232.3841653785. The cubic root of 688137979 is about 882.8600040466.

The spelling of 688137979 in words is "six hundred eighty-eight million, one hundred thirty-seven thousand, nine hundred seventy-nine".