1981187 has 12 divisors (see below), whose sum is σ = 2261880. Its totient is φ = 1729728.

The previous prime is 1981181. The next prime is 1981201. The reversal of 1981187 is 7811891.

It is not a de Polignac number, because 1981187 - 2¹² = 1977091 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1981181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2903 + ... + 3519.

It is an arithmetic number, because the mean of its divisors is an integer number (188490).

2^1981187 is an apocalyptic number.

1981187 is a deficient number, since it is larger than the sum of its proper divisors (280693).

1981187 is a wasteful number, since it uses less digits than its factorization.

1981187 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 662 (or 649 counting only the distinct ones).

The product of its digits is 4032, while the sum is 35.

The square root of 1981187 is about 1407.5464468358. The cubic root of 1981187 is about 125.5958115565.

The spelling of 1981187 in words is "one million, nine hundred eighty-one thousand, one hundred eighty-seven".