688215139 has 2 divisors, whose sum is σ = 688215140. Its totient is φ = 688215138.

The previous prime is 688215107. The next prime is 688215149. The reversal of 688215139 is 931512886.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 688215139 - 2⁵ = 688215107 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 688215095 and 688215104.

It is not a weakly prime, because it can be changed into another prime (688215149) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 344107569 + 344107570.

It is an arithmetic number, because the mean of its divisors is an integer number (344107570).

Almost surely, 2^688215139 is an apocalyptic number.

688215139 is a deficient number, since it is larger than the sum of its proper divisors (1).

688215139 is an equidigital number, since it uses as much as digits as its factorization.

688215139 is an evil number, because the sum of its binary digits is even.

The product of its digits is 103680, while the sum is 43.

The square root of 688215139 is about 26233.8548253969. The cubic root of 688215139 is about 882.8930007876.

The spelling of 688215139 in words is "six hundred eighty-eight million, two hundred fifteen thousand, one hundred thirty-nine".