640420653 has 8 divisors (see below), whose sum is σ = 854169408. Its totient is φ = 426809504.

The previous prime is 640420621. The next prime is 640420673. The reversal of 640420653 is 356024046.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 640420653 - 2⁵ = 640420621 is a prime.

It is a super-2 number, since 2×640420653² = 820277225577892818, which contains 22 as substring.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 640420653.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640420673) 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 7 ways as a sum of consecutive naturals, for example, 23001 + ... + 42542.

It is an arithmetic number, because the mean of its divisors is an integer number (106771176).

Almost surely, 2^640420653 is an apocalyptic number.

It is an amenable number.

640420653 is a deficient number, since it is larger than the sum of its proper divisors (213748755).

640420653 is a wasteful number, since it uses less digits than its factorization.

640420653 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68803.

The product of its (nonzero) digits is 17280, while the sum is 30.

The square root of 640420653 is about 25306.5338005820. The cubic root of 640420653 is about 861.9626407906.

Adding to 640420653 its reverse (356024046), we get a palindrome (996444699).

The spelling of 640420653 in words is "six hundred forty million, four hundred twenty thousand, six hundred fifty-three".