644434362433421 has 8 divisors (see below), whose sum is σ = 756401722702080. Its totient is φ = 537443329287888.

The previous prime is 644434362433417. The next prime is 644434362433423. The reversal of 644434362433421 is 124334263434446.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 644434362433421 - 2² = 644434362433417 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644434362433423) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1244081780501 + ... + 1244081781018.

It is an arithmetic number, because the mean of its divisors is an integer number (94550215337760).

Almost surely, 2^{644434362433421} is an apocalyptic number.

It is an amenable number.

644434362433421 is a deficient number, since it is larger than the sum of its proper divisors (111967360268659).

644434362433421 is a wasteful number, since it uses less digits than its factorization.

644434362433421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2488163561563.

The product of its digits is 47775744, while the sum is 53.

The spelling of 644434362433421 in words is "six hundred forty-four trillion, four hundred thirty-four billion, three hundred sixty-two million, four hundred thirty-three thousand, four hundred twenty-one".