646940709 has 32 divisors (see below), whose sum is σ = 1010672000. Its totient is φ = 407866752.

The previous prime is 646940683. The next prime is 646940713. The reversal of 646940709 is 907049646.

It is not a de Polignac number, because 646940709 - 2¹¹ = 646938661 is a prime.

It is a super-2 number, since 2×646940709² = 837064561922845362, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646940309) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 572457 + ... + 573585.

It is an arithmetic number, because the mean of its divisors is an integer number (31583500).

Almost surely, 2^646940709 is an apocalyptic number.

It is an amenable number.

646940709 is a deficient number, since it is larger than the sum of its proper divisors (363731291).

646940709 is a wasteful number, since it uses less digits than its factorization.

646940709 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2274 (or 2268 counting only the distinct ones).

The product of its (nonzero) digits is 326592, while the sum is 45.

The square root of 646940709 is about 25435.0291723835. The cubic root of 646940709 is about 864.8779535338.

The spelling of 646940709 in words is "six hundred forty-six million, nine hundred forty thousand, seven hundred nine".