1998780 has 48 divisors (see below), whose sum is σ = 6397440. Its totient is φ = 456768.

The previous prime is 1998761. The next prime is 1998793. The reversal of 1998780 is 878991.

It is a hoax number, since the sum of its digits (42) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1960 + ... + 2799.

It is an arithmetic number, because the mean of its divisors is an integer number (133280).

2^1998780 is an apocalyptic number.

1998780 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1998780 is an abundant number, since it is smaller than the sum of its proper divisors (4398660).

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

1998780 is a wasteful number, since it uses less digits than its factorization.

1998780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4778 (or 4776 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 42.

The square root of 1998780 is about 1413.7821614379. The cubic root of 1998780 is about 125.9664813840.

The spelling of 1998780 in words is "one million, nine hundred ninety-eight thousand, seven hundred eighty".