646641899 has 2 divisors, whose sum is σ = 646641900. Its totient is φ = 646641898.

The previous prime is 646641893. The next prime is 646641901. The reversal of 646641899 is 998146646.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 646641899 - 2⁴ = 646641883 is a prime.

Together with 646641901, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 646641899.

It is not a weakly prime, because it can be changed into another prime (646641893) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323320949 + 323320950.

It is an arithmetic number, because the mean of its divisors is an integer number (323320950).

Almost surely, 2^646641899 is an apocalyptic number.

646641899 is a deficient number, since it is larger than the sum of its proper divisors (1).

646641899 is an equidigital number, since it uses as much as digits as its factorization.

646641899 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2239488, while the sum is 53.

The square root of 646641899 is about 25429.1545081625. The cubic root of 646641899 is about 864.7447759609.

The spelling of 646641899 in words is "six hundred forty-six million, six hundred forty-one thousand, eight hundred ninety-nine".