643281792 has 32 divisors (see below), whose sum is σ = 1708718280. Its totient is φ = 214427136.

The previous prime is 643281791. The next prime is 643281811. The reversal of 643281792 is 297182346.

It is a tau number, because it is divible by the number of its divisors (32).

It is a super-2 number, since 2×643281792² = 827622927837462528, which contains 22 as substring.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643281791) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 837223 + ... + 837990.

Almost surely, 2^643281792 is an apocalyptic number.

It is an amenable number.

643281792 is an abundant number, since it is smaller than the sum of its proper divisors (1065436488).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

643281792 is a wasteful number, since it uses less digits than its factorization.

643281792 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1675230 (or 1675218 counting only the distinct ones).

The product of its digits is 145152, while the sum is 42.

The square root of 643281792 is about 25363.0004534164. Note that the first 3 decimals coincide. The cubic root of 643281792 is about 863.2443667692.

The spelling of 643281792 in words is "six hundred forty-three million, two hundred eighty-one thousand, seven hundred ninety-two".