1981790 has 8 divisors (see below), whose sum is σ = 3567240. Its totient is φ = 792712.

The previous prime is 1981787. The next prime is 1981813. The reversal of 1981790 is 971891.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1981790.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 99080 + ... + 99099.

It is an arithmetic number, because the mean of its divisors is an integer number (445905).

2^1981790 is an apocalyptic number.

1981790 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1981790 is a deficient number, since it is larger than the sum of its proper divisors (1585450).

1981790 is a wasteful number, since it uses less digits than its factorization.

1981790 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 198186.

The product of its (nonzero) digits is 4536, while the sum is 35.

The square root of 1981790 is about 1407.7606330623. The cubic root of 1981790 is about 125.6085525029.

The spelling of 1981790 in words is "one million, nine hundred eighty-one thousand, seven hundred ninety".