681640479 has 24 divisors (see below), whose sum is σ = 1061244912. Its totient is φ = 419109120.

The previous prime is 681640441. The next prime is 681640481. The reversal of 681640479 is 974046186.

It is not a de Polignac number, because 681640479 - 2¹⁷ = 681509407 is a prime.

It is a super-2 number, since 2×681640479² = 929267485222698882, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681640439) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 210279 + ... + 213495.

It is an arithmetic number, because the mean of its divisors is an integer number (44218538).

Almost surely, 2^681640479 is an apocalyptic number.

681640479 is a deficient number, since it is larger than the sum of its proper divisors (379604433).

681640479 is a wasteful number, since it uses less digits than its factorization.

681640479 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5047 (or 5044 counting only the distinct ones).

The product of its (nonzero) digits is 290304, while the sum is 45.

The square root of 681640479 is about 26108.2454217054. The cubic root of 681640479 is about 880.0725142552.

The spelling of 681640479 in words is "six hundred eighty-one million, six hundred forty thousand, four hundred seventy-nine".