640449489 has 4 divisors (see below), whose sum is σ = 853932656. Its totient is φ = 426966324.

The previous prime is 640449389. The next prime is 640449503. The reversal of 640449489 is 984944046.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 640449489 - 2⁷ = 640449361 is a prime.

It is a super-2 number, since 2×640449489² = 820351095920722242, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (640449289) 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, 106741579 + ... + 106741584.

It is an arithmetic number, because the mean of its divisors is an integer number (213483164).

Almost surely, 2^640449489 is an apocalyptic number.

It is an amenable number.

640449489 is a deficient number, since it is larger than the sum of its proper divisors (213483167).

640449489 is a wasteful number, since it uses less digits than its factorization.

640449489 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 213483166.

The product of its (nonzero) digits is 995328, while the sum is 48.

The square root of 640449489 is about 25307.1035284562. The cubic root of 640449489 is about 861.9755776946.

The spelling of 640449489 in words is "six hundred forty million, four hundred forty-nine thousand, four hundred eighty-nine".