644364221435 has 64 divisors (see below), whose sum is σ = 854255808000. Its totient is φ = 462725345280.

The previous prime is 644364221387. The next prime is 644364221441. The reversal of 644364221435 is 534122463446.

It is a happy number.

It is not a de Polignac number, because 644364221435 - 2¹⁰ = 644364220411 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1291310816 + ... + 1291311314.

It is an arithmetic number, because the mean of its divisors is an integer number (13347747000).

Almost surely, 2^644364221435 is an apocalyptic number.

644364221435 is a deficient number, since it is larger than the sum of its proper divisors (209891586565).

644364221435 is a wasteful number, since it uses less digits than its factorization.

644364221435 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1388.

The product of its digits is 1658880, while the sum is 44.

The spelling of 644364221435 in words is "six hundred forty-four billion, three hundred sixty-four million, two hundred twenty-one thousand, four hundred thirty-five".