646211909 has 4 divisors (see below), whose sum is σ = 738527904. Its totient is φ = 553895916.

The previous prime is 646211873. The next prime is 646211911. The reversal of 646211909 is 909112646.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 646211909 - 2⁸ = 646211653 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646211999) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 46157987 + ... + 46158000.

It is an arithmetic number, because the mean of its divisors is an integer number (184631976).

Almost surely, 2^646211909 is an apocalyptic number.

It is an amenable number.

646211909 is a deficient number, since it is larger than the sum of its proper divisors (92315995).

646211909 is an equidigital number, since it uses as much as digits as its factorization.

646211909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92315994.

The product of its (nonzero) digits is 23328, while the sum is 38.

The square root of 646211909 is about 25420.6984365104. The cubic root of 646211909 is about 864.5530603428.

The spelling of 646211909 in words is "six hundred forty-six million, two hundred eleven thousand, nine hundred nine".