1780640 has 48 divisors (see below), whose sum is σ = 4354560. Its totient is φ = 687360.

The previous prime is 1780633. The next prime is 1780643. The reversal of 1780640 is 460871.

It is not an unprimeable number, because it can be changed into a prime (1780643) 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, 4781 + ... + 5139.

It is an arithmetic number, because the mean of its divisors is an integer number (90720).

2^1780640 is an apocalyptic number.

1780640 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 1780640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2177280).

1780640 is an abundant number, since it is smaller than the sum of its proper divisors (2573920).

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

1780640 is a wasteful number, since it uses less digits than its factorization.

1780640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 405 (or 397 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 26.

The square root of 1780640 is about 1334.4062349974. The cubic root of 1780640 is about 121.2063505334.

The spelling of 1780640 in words is "one million, seven hundred eighty thousand, six hundred forty".