691656407851 has 2 divisors, whose sum is σ = 691656407852. Its totient is φ = 691656407850.

The previous prime is 691656407843. The next prime is 691656407881. The reversal of 691656407851 is 158704656196.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 691656407851 - 2³ = 691656407843 is a prime.

It is not a weakly prime, because it can be changed into another prime (691656407881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345828203925 + 345828203926.

It is an arithmetic number, because the mean of its divisors is an integer number (345828203926).

Almost surely, 2^691656407851 is an apocalyptic number.

691656407851 is a deficient number, since it is larger than the sum of its proper divisors (1).

691656407851 is an equidigital number, since it uses as much as digits as its factorization.

691656407851 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10886400, while the sum is 58.

The spelling of 691656407851 in words is "six hundred ninety-one billion, six hundred fifty-six million, four hundred seven thousand, eight hundred fifty-one".