681639061 has 2 divisors, whose sum is σ = 681639062. Its totient is φ = 681639060.

The previous prime is 681639059. The next prime is 681639103. The reversal of 681639061 is 160936186.

681639061 is nontrivially palindromic in base 12.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 416568100 + 265070961 = 20410^2 + 16281^2 .

It is a cyclic number.

It is not a de Polignac number, because 681639061 - 2¹ = 681639059 is a prime.

Together with 681639059, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (685639061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340819530 + 340819531.

It is an arithmetic number, because the mean of its divisors is an integer number (340819531).

Almost surely, 2^681639061 is an apocalyptic number.

It is an amenable number.

681639061 is a deficient number, since it is larger than the sum of its proper divisors (1).

681639061 is an equidigital number, since it uses as much as digits as its factorization.

681639061 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 46656, while the sum is 40.

The square root of 681639061 is about 26108.2182655194. The cubic root of 681639061 is about 880.0719039903.

The spelling of 681639061 in words is "six hundred eighty-one million, six hundred thirty-nine thousand, sixty-one".