681209999 has 8 divisors (see below), whose sum is σ = 698227200. Its totient is φ = 664246296.

The previous prime is 681209987. The next prime is 681210001. The reversal of 681209999 is 999902186.

It is a Cunningham number, because it is equal to 26100²-1.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-681209999 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 681209999.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681509999) 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, 13052 + ... + 39150.

It is an arithmetic number, because the mean of its divisors is an integer number (87278400).

Almost surely, 2^681209999 is an apocalyptic number.

681209999 is a deficient number, since it is larger than the sum of its proper divisors (17017201).

681209999 is a wasteful number, since it uses less digits than its factorization.

681209999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26749.

The product of its (nonzero) digits is 629856, while the sum is 53.

The square root of 681209999 is about 26099.9999808429. Note that the first 4 decimals coincide. The cubic root of 681209999 is about 879.8872096316.

The spelling of 681209999 in words is "six hundred eighty-one million, two hundred nine thousand, nine hundred ninety-nine".