644003346334666 has 4 divisors (see below), whose sum is σ = 966005019502002. Its totient is φ = 322001673167332.

The previous prime is 644003346334633. The next prime is 644003346334727. The reversal of 644003346334666 is 666433643300446.

It is a happy number.

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

It can be written as a sum of positive squares in only one way, i.e., 357176774572641 + 286826571762025 = 18899121^2 + 16935955^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 644003346334666.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 161000836583665 + ... + 161000836583668.

Almost surely, 2^{644003346334666} is an apocalyptic number.

644003346334666 is a deficient number, since it is larger than the sum of its proper divisors (322001673167336).

644003346334666 is a wasteful number, since it uses less digits than its factorization.

644003346334666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 322001673167335.

The product of its (nonzero) digits is 161243136, while the sum is 58.

The spelling of 644003346334666 in words is "six hundred forty-four trillion, three billion, three hundred forty-six million, three hundred thirty-four thousand, six hundred sixty-six".