640444249 has 3 divisors (see below), whose sum is σ = 640469557. Its totient is φ = 640418942.

The previous prime is 640444243. The next prime is 640444261. The reversal of 640444249 is 942444046.

The square root of 640444249 is 25307.

It is a perfect power (a square), and thus also a powerful number.

640444249 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 640444249 - 2¹³ = 640436057 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640444243) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 12654 + ... + 37960.

Almost surely, 2^640444249 is an apocalyptic number.

640444249 is the 25307-th square number.

640444249 is the 12654-th centered octagonal number.

It is an amenable number.

640444249 is a deficient number, since it is larger than the sum of its proper divisors (25308).

640444249 is an frugal number, since it uses more digits than its factorization.

640444249 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50614 (or 25307 counting only the distinct ones).

The product of its (nonzero) digits is 110592, while the sum is 37.

The cubic root of 640444249 is about 861.9732268643.

It can be divided in two parts, 6404 and 44249, that added together give a cube (50653 = 37³).

The spelling of 640444249 in words is "six hundred forty million, four hundred forty-four thousand, two hundred forty-nine".