646499991 has 8 divisors (see below), whose sum is σ = 866086144. Its totient is φ = 428956920.

The previous prime is 646499957. The next prime is 646499999. The reversal of 646499991 is 199994646.

646499991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 646499991 - 2⁷ = 646499863 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646499999) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 510031 + ... + 511296.

It is an arithmetic number, because the mean of its divisors is an integer number (108260768).

Almost surely, 2^646499991 is an apocalyptic number.

646499991 is a deficient number, since it is larger than the sum of its proper divisors (219586153).

646499991 is a wasteful number, since it uses less digits than its factorization.

646499991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1021541.

The product of its digits is 3779136, while the sum is 57.

The square root of 646499991 is about 25426.3640932006. The cubic root of 646499991 is about 864.6815141671.

The spelling of 646499991 in words is "six hundred forty-six million, four hundred ninety-nine thousand, nine hundred ninety-one".