644362640001 has 36 divisors (see below), whose sum is σ = 968398684500. Its totient is φ = 428728912416.

The previous prime is 644362639997. The next prime is 644362640101. The reversal of 644362640001 is 100046263446.

644362640001 is a `hidden beast` number, since 6 + 4 + 4 + 3 + 6 + 2 + 640 + 0 + 0 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 476377420401 + 167985219600 = 690201^2 + 409860^2 .

It is not a de Polignac number, because 644362640001 - 2² = 644362639997 is a prime.

It is not an unprimeable number, because it can be changed into a prime (644362640101) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 3243075 + ... + 3436023.

Almost surely, 2^644362640001 is an apocalyptic number.

It is an amenable number.

644362640001 is a deficient number, since it is larger than the sum of its proper divisors (324036044499).

644362640001 is an frugal number, since it uses more digits than its factorization.

644362640001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 193482 (or 193461 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 36.

The spelling of 644362640001 in words is "six hundred forty-four billion, three hundred sixty-two million, six hundred forty thousand, one".