646438547 has 4 divisors (see below), whose sum is σ = 650175360. Its totient is φ = 642701736.

The previous prime is 646438511. The next prime is 646438601. The reversal of 646438547 is 745834646.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 646438547 - 2⁸ = 646438291 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (646432547) 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 3 ways as a sum of consecutive naturals, for example, 1868147 + ... + 1868492.

It is an arithmetic number, because the mean of its divisors is an integer number (162543840).

Almost surely, 2^646438547 is an apocalyptic number.

646438547 is a deficient number, since it is larger than the sum of its proper divisors (3736813).

646438547 is a wasteful number, since it uses less digits than its factorization.

646438547 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3736812.

The product of its digits is 1935360, while the sum is 47.

The square root of 646438547 is about 25425.1557910665. The cubic root of 646438547 is about 864.6541199032.

The spelling of 646438547 in words is "six hundred forty-six million, four hundred thirty-eight thousand, five hundred forty-seven".