640022451 has 4 divisors (see below), whose sum is σ = 853363272. Its totient is φ = 426681632.

The previous prime is 640022441. The next prime is 640022459. The reversal of 640022451 is 154220046.

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

It is a cyclic number.

It is not a de Polignac number, because 640022451 - 2⁶ = 640022387 is a prime.

It is not an unprimeable number, because it can be changed into a prime (640022459) 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, 106670406 + ... + 106670411.

It is an arithmetic number, because the mean of its divisors is an integer number (213340818).

Almost surely, 2^640022451 is an apocalyptic number.

640022451 is a deficient number, since it is larger than the sum of its proper divisors (213340821).

640022451 is a wasteful number, since it uses less digits than its factorization.

640022451 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 213340820.

The product of its (nonzero) digits is 1920, while the sum is 24.

The square root of 640022451 is about 25298.6650043041. The cubic root of 640022451 is about 861.7839528143.

Adding to 640022451 its reverse (154220046), we get a palindrome (794242497).

The spelling of 640022451 in words is "six hundred forty million, twenty-two thousand, four hundred fifty-one".