640662 has 32 divisors (see below), whose sum is σ = 1482624. Its totient is φ = 182400.

The previous prime is 640649. The next prime is 640663. The reversal of 640662 is 266046.

640662 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640663) by changing a digit.

640662 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 837 + ... + 1407.

It is an arithmetic number, because the mean of its divisors is an integer number (46332).

2⁶⁴⁰⁶⁶² is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640662, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (741312).

640662 is an abundant number, since it is smaller than the sum of its proper divisors (841962).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

640662 is a wasteful number, since it uses less digits than its factorization.

640662 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 604.

The product of its (nonzero) digits is 1728, while the sum is 24.

The square root of 640662 is about 800.4136430621. The cubic root of 640662 is about 86.2070906074.

The spelling of 640662 in words is "six hundred forty thousand, six hundred sixty-two".