643749733 has 8 divisors (see below), whose sum is σ = 719401536. Its totient is φ = 570952800.

The previous prime is 643749721. The next prime is 643749739. The reversal of 643749733 is 337947346.

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

It is not a de Polignac number, because 643749733 - 2¹³ = 643741541 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643749739) 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, 713241 + ... + 714142.

It is an arithmetic number, because the mean of its divisors is an integer number (89925192).

Almost surely, 2^643749733 is an apocalyptic number.

It is an amenable number.

643749733 is a deficient number, since it is larger than the sum of its proper divisors (75651803).

643749733 is a wasteful number, since it uses less digits than its factorization.

643749733 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1427435.

The product of its digits is 1143072, while the sum is 46.

The square root of 643749733 is about 25372.2236510717. The cubic root of 643749733 is about 863.4536319929.

The spelling of 643749733 in words is "six hundred forty-three million, seven hundred forty-nine thousand, seven hundred thirty-three".