640423511 has 16 divisors (see below), whose sum is σ = 789347328. Its totient is φ = 505980000.

The previous prime is 640423429. The next prime is 640423549. The reversal of 640423511 is 115324046.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640423511 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640420511) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 63656 + ... + 73026.

It is an arithmetic number, because the mean of its divisors is an integer number (49334208).

Almost surely, 2^640423511 is an apocalyptic number.

640423511 is a deficient number, since it is larger than the sum of its proper divisors (148923817).

640423511 is a wasteful number, since it uses less digits than its factorization.

640423511 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10142.

The product of its (nonzero) digits is 2880, while the sum is 26.

The square root of 640423511 is about 25306.5902681495. The cubic root of 640423511 is about 861.9639230132.

Adding to 640423511 its reverse (115324046), we get a palindrome (755747557).

The spelling of 640423511 in words is "six hundred forty million, four hundred twenty-three thousand, five hundred eleven".