640675249 has 8 divisors (see below), whose sum is σ = 649702400. Its totient is φ = 631710576.

The previous prime is 640675247. The next prime is 640675267. The reversal of 640675249 is 942576046.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 640675249 - 2¹ = 640675247 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640675247) 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, 5227 + ... + 36175.

It is an arithmetic number, because the mean of its divisors is an integer number (81212800).

Almost surely, 2^640675249 is an apocalyptic number.

It is an amenable number.

640675249 is a deficient number, since it is larger than the sum of its proper divisors (9027151).

640675249 is a wasteful number, since it uses less digits than its factorization.

640675249 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31239.

The product of its (nonzero) digits is 362880, while the sum is 43.

The square root of 640675249 is about 25311.5635431713. The cubic root of 640675249 is about 862.0768486242.

The spelling of 640675249 in words is "six hundred forty million, six hundred seventy-five thousand, two hundred forty-nine".