643440492 has 36 divisors (see below), whose sum is σ = 1627909920. Its totient is φ = 214290912.

The previous prime is 643440467. The next prime is 643440493. The reversal of 643440492 is 294044346.

643440492 is a `hidden beast` number, since 643 + 4 + 4 + 0 + 4 + 9 + 2 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-3 number, since 3×643440492³ (a number of 27 digits) contains 333 as substring.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (643440493) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 36973 + ... + 51515.

It is an arithmetic number, because the mean of its divisors is an integer number (45219720).

Almost surely, 2^643440492 is an apocalyptic number.

It is an amenable number.

643440492 is an abundant number, since it is smaller than the sum of its proper divisors (984469428).

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

643440492 is a wasteful number, since it uses less digits than its factorization.

643440492 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15782 (or 15777 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 36.

The square root of 643440492 is about 25366.1288335449. The cubic root of 643440492 is about 863.3153494595.

The spelling of 643440492 in words is "six hundred forty-three million, four hundred forty thousand, four hundred ninety-two".