681891009 has 8 divisors (see below), whose sum is σ = 909586080. Its totient is φ = 454394976.

The previous prime is 681890983. The next prime is 681891011. The reversal of 681891009 is 900198186.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 681891009 - 2¹² = 681886913 is a prime.

It is not an unprimeable number, because it can be changed into a prime (681891079) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 41572 + ... + 55605.

It is an arithmetic number, because the mean of its divisors is an integer number (113698260).

Almost surely, 2^681891009 is an apocalyptic number.

It is an amenable number.

681891009 is a deficient number, since it is larger than the sum of its proper divisors (227695071).

681891009 is a wasteful number, since it uses less digits than its factorization.

681891009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99519.

The product of its (nonzero) digits is 31104, while the sum is 42.

The square root of 681891009 is about 26113.0428904791. The cubic root of 681891009 is about 880.1803216048.

The spelling of 681891009 in words is "six hundred eighty-one million, eight hundred ninety-one thousand, nine".