646464309731 has 4 divisors (see below), whose sum is σ = 646951473312. Its totient is φ = 645977146152.

The previous prime is 646464309703. The next prime is 646464309773. The reversal of 646464309731 is 137903464646.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 137903464646 = 2 ⋅68951732323.

It is a cyclic number.

It is not a de Polignac number, because 646464309731 - 2¹⁸ = 646464047587 is a prime.

It is a super-2 number, since 2×646464309731² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (646464309781) 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, 243579800 + ... + 243582453.

It is an arithmetic number, because the mean of its divisors is an integer number (161737868328).

Almost surely, 2^646464309731 is an apocalyptic number.

646464309731 is a deficient number, since it is larger than the sum of its proper divisors (487163581).

646464309731 is a wasteful number, since it uses less digits than its factorization.

646464309731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 487163580.

The product of its (nonzero) digits is 7838208, while the sum is 53.

The spelling of 646464309731 in words is "six hundred forty-six billion, four hundred sixty-four million, three hundred nine thousand, seven hundred thirty-one".