643731 has 8 divisors (see below), whose sum is σ = 936384. Its totient is φ = 390120.

The previous prime is 643729. The next prime is 643751. The reversal of 643731 is 137346.

643731 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is not a de Polignac number, because 643731 - 2¹ = 643729 is a prime.

It is a super-2 number, since 2×643731² = 828779200722, which contains 22 as substring.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 643731.

It is not an unprimeable number, because it can be changed into a prime (643751) 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, 9721 + ... + 9786.

It is an arithmetic number, because the mean of its divisors is an integer number (117048).

2⁶⁴³⁷³¹ is an apocalyptic number.

643731 is a deficient number, since it is larger than the sum of its proper divisors (292653).

643731 is a wasteful number, since it uses less digits than its factorization.

643731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19521.

The product of its digits is 1512, while the sum is 24.

The square root of 643731 is about 802.3284863446. The cubic root of 643731 is about 86.3445256464.

The spelling of 643731 in words is "six hundred forty-three thousand, seven hundred thirty-one".