640232823 has 4 divisors (see below), whose sum is σ = 853643768. Its totient is φ = 426821880.

The previous prime is 640232821. The next prime is 640232851. The reversal of 640232823 is 328232046.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 640232823 - 2¹ = 640232821 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640232821) 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, 106705468 + ... + 106705473.

It is an arithmetic number, because the mean of its divisors is an integer number (213410942).

Almost surely, 2^640232823 is an apocalyptic number.

640232823 is a deficient number, since it is larger than the sum of its proper divisors (213410945).

640232823 is a wasteful number, since it uses less digits than its factorization.

640232823 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 213410944.

The product of its (nonzero) digits is 13824, while the sum is 30.

The square root of 640232823 is about 25302.8224314996. The cubic root of 640232823 is about 861.8783637492.

Adding to 640232823 its reverse (328232046), we get a palindrome (968464869).

The spelling of 640232823 in words is "six hundred forty million, two hundred thirty-two thousand, eight hundred twenty-three".