646402019 has 4 divisors (see below), whose sum is σ = 646857696. Its totient is φ = 645946344.

The previous prime is 646402013. The next prime is 646402037. The reversal of 646402019 is 910204646.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-646402019 is a prime.

It is a super-2 number, since 2×646402019² = 835671140334552722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (646402013) 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 in 3 ways as a sum of consecutive naturals, for example, 225704 + ... + 228549.

It is an arithmetic number, because the mean of its divisors is an integer number (161714424).

Almost surely, 2^646402019 is an apocalyptic number.

646402019 is a deficient number, since it is larger than the sum of its proper divisors (455677).

646402019 is a wasteful number, since it uses less digits than its factorization.

646402019 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 455676.

The product of its (nonzero) digits is 10368, while the sum is 32.

The square root of 646402019 is about 25424.4374372374. The cubic root of 646402019 is about 864.6378333947.

The spelling of 646402019 in words is "six hundred forty-six million, four hundred two thousand, nineteen".