643771 has 8 divisors (see below), whose sum is σ = 676800. Its totient is φ = 611520.

The previous prime is 643751. The next prime is 643781. The reversal of 643771 is 177346.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-643771 is a prime.

It is a super-2 number, since 2×643771² = 828882200882, which contains 22 as substring.

It is a Duffinian number.

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, 2151 + ... + 2431.

It is an arithmetic number, because the mean of its divisors is an integer number (84600).

2⁶⁴³⁷⁷¹ is an apocalyptic number.

643771 is a deficient number, since it is larger than the sum of its proper divisors (33029).

643771 is a wasteful number, since it uses less digits than its factorization.

643771 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 389.

The product of its digits is 3528, while the sum is 28.

The square root of 643771 is about 802.3534134033. The cubic root of 643771 is about 86.3463140277.

The spelling of 643771 in words is "six hundred forty-three thousand, seven hundred seventy-one".