647691679 has 2 divisors, whose sum is σ = 647691680. Its totient is φ = 647691678.

The previous prime is 647691677. The next prime is 647691701. The reversal of 647691679 is 976196746.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 647691679 - 2¹ = 647691677 is a prime.

It is a super-2 number, since 2×647691679² = 839009022091678082, which contains 22 as substring.

Together with 647691677, 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 (647691677) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323845839 + 323845840.

It is an arithmetic number, because the mean of its divisors is an integer number (323845840).

Almost surely, 2^647691679 is an apocalyptic number.

647691679 is a deficient number, since it is larger than the sum of its proper divisors (1).

647691679 is an equidigital number, since it uses as much as digits as its factorization.

647691679 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3429216, while the sum is 55.

The square root of 647691679 is about 25449.7874057918. The cubic root of 647691679 is about 865.2124747849.

The spelling of 647691679 in words is "six hundred forty-seven million, six hundred ninety-one thousand, six hundred seventy-nine".