1981111 has 8 divisors (see below), whose sum is σ = 2275200. Its totient is φ = 1706040.

The previous prime is 1981099. The next prime is 1981141. The reversal of 1981111 is 1111891.

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

It is a cyclic number.

It is not a de Polignac number, because 1981111 - 2⁷ = 1980983 is a prime.

It is a Duffinian number.

1981111 is a modest number, since divided by 1111 gives 198 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981141) 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, 4531 + ... + 4948.

It is an arithmetic number, because the mean of its divisors is an integer number (284400).

2^1981111 is an apocalyptic number.

1981111 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1981111 is a deficient number, since it is larger than the sum of its proper divisors (294089).

1981111 is a wasteful number, since it uses less digits than its factorization.

1981111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9509.

The product of its digits is 72, while the sum is 22.

The square root of 1981111 is about 1407.5194492440. The cubic root of 1981111 is about 125.5942055490.

The spelling of 1981111 in words is "one million, nine hundred eighty-one thousand, one hundred eleven".