646449893 has 4 divisors (see below), whose sum is σ = 647362380. Its totient is φ = 645537408.

The previous prime is 646449883. The next prime is 646449907. The reversal of 646449893 is 398944646.

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

It can be written as a sum of positive squares in 2 ways, for example, as 196925089 + 449524804 = 14033^2 + 21202^2 .

It is a cyclic number.

It is not a de Polignac number, because 646449893 - 2¹⁶ = 646384357 is a prime.

It is a super-2 number, since 2×646449893² = 835794928319422898, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646449823) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 455180 + ... + 456597.

It is an arithmetic number, because the mean of its divisors is an integer number (161840595).

Almost surely, 2^646449893 is an apocalyptic number.

It is an amenable number.

646449893 is a deficient number, since it is larger than the sum of its proper divisors (912487).

646449893 is an equidigital number, since it uses as much as digits as its factorization.

646449893 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 912486.

The product of its digits is 4478976, while the sum is 53.

The square root of 646449893 is about 25425.3789155639. The cubic root of 646449893 is about 864.6591785476.

The spelling of 646449893 in words is "six hundred forty-six million, four hundred forty-nine thousand, eight hundred ninety-three".