646913791 has 2 divisors, whose sum is σ = 646913792. Its totient is φ = 646913790.

The previous prime is 646913789. The next prime is 646913803. The reversal of 646913791 is 197319646.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 646913791 - 2¹ = 646913789 is a prime.

Together with 646913789, it forms a pair of twin primes.

It is the 25435-th Hogben number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (646913741) by changing a digit.

It is a nontrivial repunit in base 25434.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323456895 + 323456896.

It is an arithmetic number, because the mean of its divisors is an integer number (323456896).

Almost surely, 2^646913791 is an apocalyptic number.

646913791 is a deficient number, since it is larger than the sum of its proper divisors (1).

646913791 is an equidigital number, since it uses as much as digits as its factorization.

646913791 is an evil number, because the sum of its binary digits is even.

The product of its digits is 244944, while the sum is 46.

The square root of 646913791 is about 25434.5000147438. The cubic root of 646913791 is about 864.8659580462.

The spelling of 646913791 in words is "six hundred forty-six million, nine hundred thirteen thousand, seven hundred ninety-one".