640990533 has 16 divisors (see below), whose sum is σ = 873815040. Its totient is φ = 417802944.

The previous prime is 640990529. The next prime is 640990561. The reversal of 640990533 is 335099046.

640990533 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 640990533 - 2² = 640990529 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 640990491 and 640990500.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640990583) 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, 39708 + ... + 53466.

It is an arithmetic number, because the mean of its divisors is an integer number (54613440).

Almost surely, 2^640990533 is an apocalyptic number.

It is an amenable number.

640990533 is a deficient number, since it is larger than the sum of its proper divisors (232824507).

640990533 is a wasteful number, since it uses less digits than its factorization.

640990533 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14108.

The product of its (nonzero) digits is 87480, while the sum is 39.

The square root of 640990533 is about 25317.7908396448. The cubic root of 640990533 is about 862.2182382308.

The spelling of 640990533 in words is "six hundred forty million, nine hundred ninety thousand, five hundred thirty-three".