646712209 has 24 divisors (see below), whose sum is σ = 791983080. Its totient is φ = 523944960.

The previous prime is 646712197. The next prime is 646712219. The reversal of 646712209 is 902217646.

It can be written as a sum of positive squares in 4 ways, for example, as 187553025 + 459159184 = 13695^2 + 21428^2 .

It is not a de Polignac number, because 646712209 - 2⁷ = 646712081 is a prime.

It is a hoax number, since the sum of its digits (37) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (646712219) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 38529 + ... + 52705.

It is an arithmetic number, because the mean of its divisors is an integer number (32999295).

Almost surely, 2^646712209 is an apocalyptic number.

It is an amenable number.

646712209 is a deficient number, since it is larger than the sum of its proper divisors (145270871).

646712209 is a wasteful number, since it uses less digits than its factorization.

646712209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14241 (or 14230 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 37.

The square root of 646712209 is about 25430.5369388851. The cubic root of 646712209 is about 864.7761163374.

The spelling of 646712209 in words is "six hundred forty-six million, seven hundred twelve thousand, two hundred nine".