640880449 has 4 divisors (see below), whose sum is σ = 699142320. Its totient is φ = 582618580.

The previous prime is 640880419. The next prime is 640880473. The reversal of 640880449 is 944088046.

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 a cyclic number.

It is not a de Polignac number, because 640880449 - 2⁵ = 640880417 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640880419) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 29130919 + ... + 29130940.

It is an arithmetic number, because the mean of its divisors is an integer number (174785580).

Almost surely, 2^640880449 is an apocalyptic number.

It is an amenable number.

640880449 is a deficient number, since it is larger than the sum of its proper divisors (58261871).

640880449 is a wasteful number, since it uses less digits than its factorization.

640880449 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58261870.

The product of its (nonzero) digits is 221184, while the sum is 43.

The square root of 640880449 is about 25315.6167019490. The cubic root of 640880449 is about 862.1688761566.

The spelling of 640880449 in words is "six hundred forty million, eight hundred eighty thousand, four hundred forty-nine".