644650102399 has 4 divisors (see below), whose sum is σ = 644715953280. Its totient is φ = 644584251520.

The previous prime is 644650102391. The next prime is 644650102409. The reversal of 644650102399 is 993201056446.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 993201056446 = 2 ⋅496600528223.

It is a cyclic number.

It is not a de Polignac number, because 644650102399 - 2³ = 644650102391 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 (644650102391) 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, 32910754 + ... + 32930335.

It is an arithmetic number, because the mean of its divisors is an integer number (161178988320).

Almost surely, 2^644650102399 is an apocalyptic number.

644650102399 is a deficient number, since it is larger than the sum of its proper divisors (65850881).

644650102399 is an equidigital number, since it uses as much as digits as its factorization.

644650102399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65850880.

The product of its (nonzero) digits is 1399680, while the sum is 49.

The spelling of 644650102399 in words is "six hundred forty-four billion, six hundred fifty million, one hundred two thousand, three hundred ninety-nine".