1820640 has 48 divisors (see below), whose sum is σ = 5736528. Its totient is φ = 485376.

The previous prime is 1820633. The next prime is 1820641. The reversal of 1820640 is 460281.

It is a tau number, because it is divible by the number of its divisors (48).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1820641) 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, 1417 + ... + 2376.

It is an arithmetic number, because the mean of its divisors is an integer number (119511).

2^1820640 is an apocalyptic number.

1820640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1820640 is an abundant number, since it is smaller than the sum of its proper divisors (3915888).

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

1820640 is a wasteful number, since it uses less digits than its factorization.

1820640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3811 (or 3803 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 1820640 is about 1349.3109352555. The cubic root of 1820640 is about 122.1072245549.

The spelling of 1820640 in words is "one million, eight hundred twenty thousand, six hundred forty".