643639744745 has 8 divisors (see below), whose sum is σ = 773498543616. Its totient is φ = 514157895856.

The previous prime is 643639744733. The next prime is 643639744757. The reversal of 643639744745 is 547447936346.

It is an interprime number because it is at equal distance from previous prime (643639744733) and next prime (643639744757).

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 643639744745 - 2⁶ = 643639744681 is a prime.

It is a Duffinian number.

It is a Curzon number.

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 7 ways as a sum of consecutive naturals, for example, 94233737 + ... + 94240566.

It is an arithmetic number, because the mean of its divisors is an integer number (96687317952).

Almost surely, 2^643639744745 is an apocalyptic number.

It is an amenable number.

643639744745 is a deficient number, since it is larger than the sum of its proper divisors (129858798871).

643639744745 is a wasteful number, since it uses less digits than its factorization.

643639744745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 188474991.

The product of its digits is 182891520, while the sum is 62.

The spelling of 643639744745 in words is "six hundred forty-three billion, six hundred thirty-nine million, seven hundred forty-four thousand, seven hundred forty-five".