687865891 has 2 divisors, whose sum is σ = 687865892. Its totient is φ = 687865890.

The previous prime is 687865861. The next prime is 687865901. The reversal of 687865891 is 198568786.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 687865891 - 2⁵ = 687865859 is a prime.

It is not a weakly prime, because it can be changed into another prime (687865831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343932945 + 343932946.

It is an arithmetic number, because the mean of its divisors is an integer number (343932946).

Almost surely, 2^687865891 is an apocalyptic number.

687865891 is a deficient number, since it is larger than the sum of its proper divisors (1).

687865891 is an equidigital number, since it uses as much as digits as its factorization.

687865891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5806080, while the sum is 58.

The square root of 687865891 is about 26227.1975437712. The cubic root of 687865891 is about 882.7436285099.

The spelling of 687865891 in words is "six hundred eighty-seven million, eight hundred sixty-five thousand, eight hundred ninety-one".