681157493 has 4 divisors (see below), whose sum is σ = 681223200. Its totient is φ = 681091788.

The previous prime is 681157469. The next prime is 681157501. The reversal of 681157493 is 394751186.

681157493 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 681157493 - 2¹² = 681153397 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681157693) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13505 + ... + 39302.

It is an arithmetic number, because the mean of its divisors is an integer number (170305800).

Almost surely, 2^681157493 is an apocalyptic number.

It is an amenable number.

681157493 is a deficient number, since it is larger than the sum of its proper divisors (65707).

681157493 is a wasteful number, since it uses less digits than its factorization.

681157493 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65706.

The product of its digits is 181440, while the sum is 44.

The square root of 681157493 is about 26098.9940993901. The cubic root of 681157493 is about 879.8646025330.

The spelling of 681157493 in words is "six hundred eighty-one million, one hundred fifty-seven thousand, four hundred ninety-three".