1640640 has 56 divisors (see below), whose sum is σ = 5212080. Its totient is φ = 437248.

The previous prime is 1640633. The next prime is 1640641. The reversal of 1640640 is 460461.

It is not an unprimeable number, because it can be changed into a prime (1640641) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 106 + ... + 1814.

2^1640640 is an apocalyptic number.

1640640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1640640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2606040).

1640640 is an abundant number, since it is smaller than the sum of its proper divisors (3571440).

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

1640640 is a wasteful number, since it uses less digits than its factorization.

1640640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1729 (or 1719 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 21.

The square root of 1640640 is about 1280.8747011320. The cubic root of 1640640 is about 117.9427089502.

The spelling of 1640640 in words is "one million, six hundred forty thousand, six hundred forty".