643340405 has 8 divisors (see below), whose sum is σ = 774445752. Its totient is φ = 513047488.

The previous prime is 643340381. The next prime is 643340413. The reversal of 643340405 is 504043346.

It can be written as a sum of positive squares in 4 ways, for example, as 15437041 + 627903364 = 3929^2 + 25058^2 .

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-643340405 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 201362 + ... + 204531.

It is an arithmetic number, because the mean of its divisors is an integer number (96805719).

Almost surely, 2^643340405 is an apocalyptic number.

It is an amenable number.

643340405 is a deficient number, since it is larger than the sum of its proper divisors (131105347).

643340405 is a wasteful number, since it uses less digits than its factorization.

643340405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 406215.

The product of its (nonzero) digits is 17280, while the sum is 29.

The square root of 643340405 is about 25364.1559094719. The cubic root of 643340405 is about 863.2705843129.

The spelling of 643340405 in words is "six hundred forty-three million, three hundred forty thousand, four hundred five".