640206023 has 4 divisors (see below), whose sum is σ = 644039760. Its totient is φ = 636372288.

The previous prime is 640206011. The next prime is 640206071. The reversal of 640206023 is 320602046.

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 640206023 - 2¹² = 640201927 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 640206023.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640202023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1916618 + ... + 1916951.

It is an arithmetic number, because the mean of its divisors is an integer number (161009940).

Almost surely, 2^640206023 is an apocalyptic number.

640206023 is a deficient number, since it is larger than the sum of its proper divisors (3833737).

640206023 is a wasteful number, since it uses less digits than its factorization.

640206023 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3833736.

The product of its (nonzero) digits is 1728, while the sum is 23.

The square root of 640206023 is about 25302.2928407684. The cubic root of 640206023 is about 861.8663375708.

Adding to 640206023 its reverse (320602046), we get a palindrome (960808069).

The spelling of 640206023 in words is "six hundred forty million, two hundred six thousand, twenty-three".