688691407 has 2 divisors, whose sum is σ = 688691408. Its totient is φ = 688691406.

The previous prime is 688691387. The next prime is 688691429. The reversal of 688691407 is 704196886.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 688691407 - 2⁷ = 688691279 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (688691447) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 344345703 + 344345704.

It is an arithmetic number, because the mean of its divisors is an integer number (344345704).

Almost surely, 2^688691407 is an apocalyptic number.

688691407 is a deficient number, since it is larger than the sum of its proper divisors (1).

688691407 is an equidigital number, since it uses as much as digits as its factorization.

688691407 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 580608, while the sum is 49.

The square root of 688691407 is about 26242.9306099757. The cubic root of 688691407 is about 883.0966176987.

The spelling of 688691407 in words is "six hundred eighty-eight million, six hundred ninety-one thousand, four hundred seven".