640165903 has 16 divisors (see below), whose sum is σ = 723342592. Its totient is φ = 562464000.

The previous prime is 640165901. The next prime is 640165927. The reversal of 640165903 is 309561046.

It is not a de Polignac number, because 640165903 - 2¹ = 640165901 is a prime.

It is the 25302-nd Hogben number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640165901) by changing a digit.

It is a nontrivial repunit in base 25301.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11563 + ... + 37603.

It is an arithmetic number, because the mean of its divisors is an integer number (45208912).

Almost surely, 2^640165903 is an apocalyptic number.

640165903 is a deficient number, since it is larger than the sum of its proper divisors (83176689).

640165903 is a wasteful number, since it uses less digits than its factorization.

640165903 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26146.

The product of its (nonzero) digits is 19440, while the sum is 34.

The square root of 640165903 is about 25301.5000148213. The cubic root of 640165903 is about 861.8483335749.

The spelling of 640165903 in words is "six hundred forty million, one hundred sixty-five thousand, nine hundred three".