64644640309 has 4 divisors (see below), whose sum is σ = 64645753216. Its totient is φ = 64643527404.

The previous prime is 64644640303. The next prime is 64644640321. The reversal of 64644640309 is 90304644646.

It is a happy number.

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 a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-64644640309 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 (64644640303) 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, 464229 + ... + 587194.

It is an arithmetic number, because the mean of its divisors is an integer number (16161438304).

Almost surely, 2^64644640309 is an apocalyptic number.

It is an amenable number.

64644640309 is a deficient number, since it is larger than the sum of its proper divisors (1112907).

64644640309 is a wasteful number, since it uses less digits than its factorization.

64644640309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1112906.

The product of its (nonzero) digits is 1492992, while the sum is 46.

The spelling of 64644640309 in words is "sixty-four billion, six hundred forty-four million, six hundred forty thousand, three hundred nine".