681621738 has 32 divisors (see below), whose sum is σ = 1608253440. Its totient is φ = 188466480.

The previous prime is 681621737. The next prime is 681621739. The reversal of 681621738 is 837126186.

It is an interprime number because it is at equal distance from previous prime (681621737) and next prime (681621739).

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 681621738.

It is not an unprimeable number, because it can be changed into a prime (681621737) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 260458 + ... + 263061.

It is an arithmetic number, because the mean of its divisors is an integer number (50257920).

Almost surely, 2^681621738 is an apocalyptic number.

681621738 is an abundant number, since it is smaller than the sum of its proper divisors (926631702).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

681621738 is a wasteful number, since it uses less digits than its factorization.

681621738 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 523562.

The product of its digits is 96768, while the sum is 42.

The square root of 681621738 is about 26107.8865096354. The cubic root of 681621738 is about 880.0644486201.

The spelling of 681621738 in words is "six hundred eighty-one million, six hundred twenty-one thousand, seven hundred thirty-eight".