64640443 has 32 divisors (see below), whose sum is σ = 82145664. Its totient is φ = 49600512.

The previous prime is 64640437. The next prime is 64640473. The reversal of 64640443 is 34404646.

It is a cyclic number.

It is not a de Polignac number, because 64640443 - 2¹⁷ = 64509371 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (64640473) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 233221 + ... + 233497.

It is an arithmetic number, because the mean of its divisors is an integer number (2567052).

Almost surely, 2^64640443 is an apocalyptic number.

64640443 is a deficient number, since it is larger than the sum of its proper divisors (17505221).

64640443 is a wasteful number, since it uses less digits than its factorization.

64640443 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 391.

The product of its (nonzero) digits is 27648, while the sum is 31.

The square root of 64640443 is about 8039.9280469417. The cubic root of 64640443 is about 401.3298302295.

The spelling of 64640443 in words is "sixty-four million, six hundred forty thousand, four hundred forty-three".