1780840 has 24 divisors (see below), whose sum is σ = 4025970. Its totient is φ = 708960.

The previous prime is 1780837. The next prime is 1780873. The reversal of 1780840 is 480871.

It can be written as a sum of positive squares in only one way, i.e., 1602756 + 178084 = 1266^2 + 422^2 .

It is a super-2 number, since 2×1780840² = 6342782211200, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1780799 and 1780808.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 8335 + ... + 8545.

2^1780840 is an apocalyptic number.

1780840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1780840 is an abundant number, since it is smaller than the sum of its proper divisors (2245130).

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

1780840 is an equidigital number, since it uses as much as digits as its factorization.

1780840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 433 (or 218 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 28.

The square root of 1780840 is about 1334.4811725911. The cubic root of 1780840 is about 121.2108882955.

The spelling of 1780840 in words is "one million, seven hundred eighty thousand, eight hundred forty".