681593940 has 60 divisors (see below), whose sum is σ = 2138190516. Its totient is φ = 181757952.

The previous prime is 681593921. The next prime is 681593981. The reversal of 681593940 is 49395186.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 297355536 + 384238404 = 17244^2 + 19602^2 .

It is a tau number, because it is divible by the number of its divisors (60).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 208749 + ... + 211988.

Almost surely, 2^681593940 is an apocalyptic number.

681593940 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

681593940 is an abundant number, since it is smaller than the sum of its proper divisors (1456596576).

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

681593940 is a wasteful number, since it uses less digits than its factorization.

681593940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 420758 (or 420747 counting only the distinct ones).

The product of its (nonzero) digits is 233280, while the sum is 45.

The square root of 681593940 is about 26107.3541363348. The cubic root of 681593940 is about 880.0524848173.

The spelling of 681593940 in words is "six hundred eighty-one million, five hundred ninety-three thousand, nine hundred forty".