681889729 has 4 divisors (see below), whose sum is σ = 682632640. Its totient is φ = 681146820.

The previous prime is 681889667. The next prime is 681889739. The reversal of 681889729 is 927988186.

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.

It is a cyclic number.

It is not a de Polignac number, because 681889729 - 2²⁷ = 547672001 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (681889739) 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, 370077 + ... + 371914.

It is an arithmetic number, because the mean of its divisors is an integer number (170658160).

Almost surely, 2^681889729 is an apocalyptic number.

It is an amenable number.

681889729 is a deficient number, since it is larger than the sum of its proper divisors (742911).

681889729 is an equidigital number, since it uses as much as digits as its factorization.

681889729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 742910.

The product of its digits is 3483648, while the sum is 58.

The square root of 681889729 is about 26113.0183816425. The cubic root of 681889729 is about 880.1797708660.

The spelling of 681889729 in words is "six hundred eighty-one million, eight hundred eighty-nine thousand, seven hundred twenty-nine".