855721687 has 2 divisors, whose sum is σ = 855721688. Its totient is φ = 855721686.

The previous prime is 855721679. The next prime is 855721697. The reversal of 855721687 is 786127558.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 855721687 - 2³ = 855721679 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 855721687.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (855721637) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 427860843 + 427860844.

It is an arithmetic number, because the mean of its divisors is an integer number (427860844).

Almost surely, 2^855721687 is an apocalyptic number.

855721687 is a deficient number, since it is larger than the sum of its proper divisors (1).

855721687 is an equidigital number, since it uses as much as digits as its factorization.

855721687 is an evil number, because the sum of its binary digits is even.

The product of its digits is 940800, while the sum is 49.

The square root of 855721687 is about 29252.7210187360. The cubic root of 855721687 is about 949.3889651494.

The spelling of 855721687 in words is "eight hundred fifty-five million, seven hundred twenty-one thousand, six hundred eighty-seven".