640633559 has 16 divisors (see below), whose sum is σ = 711488448. Its totient is φ = 573737472.

The previous prime is 640633549. The next prime is 640633573. The reversal of 640633559 is 955336046.

It is a cyclic number.

It is not a de Polignac number, because 640633559 - 2²⁰ = 639584983 is a prime.

It is a super-2 number, since 2×640633559² = 820822713834012962, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640633549) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 72869 + ... + 81185.

It is an arithmetic number, because the mean of its divisors is an integer number (44468028).

Almost surely, 2^640633559 is an apocalyptic number.

640633559 is a deficient number, since it is larger than the sum of its proper divisors (70854889).

640633559 is a wasteful number, since it uses less digits than its factorization.

640633559 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8554.

The product of its (nonzero) digits is 291600, while the sum is 41.

The square root of 640633559 is about 25310.7399931333. The cubic root of 640633559 is about 862.0581492059.

It can be divided in two parts, 6406335 and 59, that multiplied together give a triangular number (377973765 = T₂₇₄₉₄).

The spelling of 640633559 in words is "six hundred forty million, six hundred thirty-three thousand, five hundred fifty-nine".