644899499 has 4 divisors (see below), whose sum is σ = 648140400. Its totient is φ = 641658600.

The previous prime is 644899487. The next prime is 644899517. The reversal of 644899499 is 994998446.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 644899499 - 2¹⁶ = 644833963 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644899399) 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, 1620152 + ... + 1620549.

It is an arithmetic number, because the mean of its divisors is an integer number (162035100).

Almost surely, 2^644899499 is an apocalyptic number.

644899499 is a deficient number, since it is larger than the sum of its proper divisors (3240901).

644899499 is a wasteful number, since it uses less digits than its factorization.

644899499 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3240900.

The product of its digits is 20155392, while the sum is 62.

The square root of 644899499 is about 25394.8715098147. The cubic root of 644899499 is about 863.9673819383.

The spelling of 644899499 in words is "six hundred forty-four million, eight hundred ninety-nine thousand, four hundred ninety-nine".