685639651 has 2 divisors, whose sum is σ = 685639652. Its totient is φ = 685639650.

The previous prime is 685639639. The next prime is 685639693. The reversal of 685639651 is 156936586.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 685639651 - 2¹³ = 685631459 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 685639595 and 685639604.

It is not a weakly prime, because it can be changed into another prime (685639051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342819825 + 342819826.

It is an arithmetic number, because the mean of its divisors is an integer number (342819826).

Almost surely, 2^685639651 is an apocalyptic number.

685639651 is a deficient number, since it is larger than the sum of its proper divisors (1).

685639651 is an equidigital number, since it uses as much as digits as its factorization.

685639651 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1166400, while the sum is 49.

The square root of 685639651 is about 26184.7217094244. The cubic root of 685639651 is about 881.7902822701.

The spelling of 685639651 in words is "six hundred eighty-five million, six hundred thirty-nine thousand, six hundred fifty-one".