640605023 has 16 divisors (see below), whose sum is σ = 660842496. Its totient is φ = 620780160.

The previous prime is 640604989. The next prime is 640605047. The reversal of 640605023 is 320506046.

It is a cyclic number.

It is not a de Polignac number, because 640605023 - 2⁶ = 640604959 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 640604983 and 640605001.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640605923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1445840 + ... + 1446282.

It is an arithmetic number, because the mean of its divisors is an integer number (41302656).

Almost surely, 2^640605023 is an apocalyptic number.

640605023 is a deficient number, since it is larger than the sum of its proper divisors (20237473).

640605023 is a wasteful number, since it uses less digits than its factorization.

640605023 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 814.

The product of its (nonzero) digits is 4320, while the sum is 26.

The square root of 640605023 is about 25310.1762735861. The cubic root of 640605023 is about 862.0453493475.

The spelling of 640605023 in words is "six hundred forty million, six hundred five thousand, twenty-three".