646903891 has 2 divisors, whose sum is σ = 646903892. Its totient is φ = 646903890.

The previous prime is 646903883. The next prime is 646903897. The reversal of 646903891 is 198309646.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 646903891 - 2³ = 646903883 is a prime.

It is not a weakly prime, because it can be changed into another prime (646903897) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323451945 + 323451946.

It is an arithmetic number, because the mean of its divisors is an integer number (323451946).

Almost surely, 2^646903891 is an apocalyptic number.

646903891 is a deficient number, since it is larger than the sum of its proper divisors (1).

646903891 is an equidigital number, since it uses as much as digits as its factorization.

646903891 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 279936, while the sum is 46.

The square root of 646903891 is about 25434.3053964522. The cubic root of 646903891 is about 864.8615462185.

The spelling of 646903891 in words is "six hundred forty-six million, nine hundred three thousand, eight hundred ninety-one".