640156 has 12 divisors (see below), whose sum is σ = 1222200. Its totient is φ = 290960.

The previous prime is 640153. The next prime is 640163. The reversal of 640156 is 651046.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640151) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7231 + ... + 7318.

It is an arithmetic number, because the mean of its divisors is an integer number (101850).

2⁶⁴⁰¹⁵⁶ is an apocalyptic number.

It is an amenable number.

640156 is a deficient number, since it is larger than the sum of its proper divisors (582044).

640156 is a wasteful number, since it uses less digits than its factorization.

640156 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14564 (or 14562 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 640156 is about 800.0974940593. The cubic root of 640156 is about 86.1843889452.

The spelling of 640156 in words is "six hundred forty thousand, one hundred fifty-six".