1981864 has 16 divisors (see below), whose sum is σ = 3877920. Its totient is φ = 947760.

The previous prime is 1981853. The next prime is 1981867. The reversal of 1981864 is 4681891.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (1981867) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5202 + ... + 5569.

It is an arithmetic number, because the mean of its divisors is an integer number (242370).

2^1981864 is an apocalyptic number.

It is an amenable number.

1981864 is a deficient number, since it is larger than the sum of its proper divisors (1896056).

1981864 is a wasteful number, since it uses less digits than its factorization.

1981864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10800 (or 10796 counting only the distinct ones).

The product of its digits is 13824, while the sum is 37.

The square root of 1981864 is about 1407.7869156943. The cubic root of 1981864 is about 125.6101158904.

The spelling of 1981864 in words is "one million, nine hundred eighty-one thousand, eight hundred sixty-four".