640234533 has 4 divisors (see below), whose sum is σ = 853646048. Its totient is φ = 426823020.

The previous prime is 640234531. The next prime is 640234571. The reversal of 640234533 is 335432046.

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 640234533 - 2¹ = 640234531 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 640234533.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640234531) 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, 106705753 + ... + 106705758.

It is an arithmetic number, because the mean of its divisors is an integer number (213411512).

Almost surely, 2^640234533 is an apocalyptic number.

It is an amenable number.

640234533 is a deficient number, since it is larger than the sum of its proper divisors (213411515).

640234533 is a wasteful number, since it uses less digits than its factorization.

640234533 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 213411514.

The product of its (nonzero) digits is 25920, while the sum is 30.

The square root of 640234533 is about 25302.8562221738. The cubic root of 640234533 is about 861.8791310798.

Adding to 640234533 its reverse (335432046), we get a palindrome (975666579).

The spelling of 640234533 in words is "six hundred forty million, two hundred thirty-four thousand, five hundred thirty-three".