681206681 has 4 divisors (see below), whose sum is σ = 686406864. Its totient is φ = 676006500.

The previous prime is 681206633. The next prime is 681206699. The reversal of 681206681 is 186602186.

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 an emirpimes, since its reverse is a distinct semiprime: 186602186 = 2 ⋅93301093.

It is a cyclic number.

It is not a de Polignac number, because 681206681 - 2¹⁴ = 681190297 is a prime.

It is a super-2 number, since 2×681206681² = 928085084478071522, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (681206081) 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, 2599895 + ... + 2600156.

It is an arithmetic number, because the mean of its divisors is an integer number (171601716).

Almost surely, 2^681206681 is an apocalyptic number.

It is an amenable number.

681206681 is a deficient number, since it is larger than the sum of its proper divisors (5200183).

681206681 is a wasteful number, since it uses less digits than its factorization.

681206681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5200182.

The product of its (nonzero) digits is 27648, while the sum is 38.

The square root of 681206681 is about 26099.9364175471. The cubic root of 681206681 is about 879.8857810607.

The spelling of 681206681 in words is "six hundred eighty-one million, two hundred six thousand, six hundred eighty-one".