1981611 has 16 divisors (see below), whose sum is σ = 3064320. Its totient is φ = 1263240.

The previous prime is 1981607. The next prime is 1981619. The reversal of 1981611 is 1161891.

It is not a de Polignac number, because 1981611 - 2² = 1981607 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

1981611 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (1981619) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 975 + ... + 2216.

It is an arithmetic number, because the mean of its divisors is an integer number (191520).

2^1981611 is an apocalyptic number.

1981611 is a deficient number, since it is larger than the sum of its proper divisors (1082709).

1981611 is a wasteful number, since it uses less digits than its factorization.

1981611 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3223 (or 3217 counting only the distinct ones).

The product of its digits is 432, while the sum is 27.

The square root of 1981611 is about 1407.6970554775. The cubic root of 1981611 is about 125.6047706344.

The spelling of 1981611 in words is "one million, nine hundred eighty-one thousand, six hundred eleven".