646138649 has 16 divisors (see below), whose sum is σ = 709128000. Its totient is φ = 585149376.

The previous prime is 646138579. The next prime is 646138667. The reversal of 646138649 is 946831646.

It is a cyclic number.

It is not a de Polignac number, because 646138649 - 2²⁰ = 645090073 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (646138699) 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 15 ways as a sum of consecutive naturals, for example, 158762 + ... + 162780.

It is an arithmetic number, because the mean of its divisors is an integer number (44320500).

Almost surely, 2^646138649 is an apocalyptic number.

It is an amenable number.

646138649 is a deficient number, since it is larger than the sum of its proper divisors (62989351).

646138649 is a wasteful number, since it uses less digits than its factorization.

646138649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4264.

The product of its digits is 746496, while the sum is 47.

The square root of 646138649 is about 25419.2574439144. The cubic root of 646138649 is about 864.5203881136.

The spelling of 646138649 in words is "six hundred forty-six million, one hundred thirty-eight thousand, six hundred forty-nine".