1981538 has 8 divisors (see below), whose sum is σ = 3200988. Its totient is φ = 914544.

The previous prime is 1981523. The next prime is 1981543. The reversal of 1981538 is 8351891.

It can be written as a sum of positive squares in 2 ways, for example, as 1951609 + 29929 = 1397^2 + 173^2 .

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

It is an Ulam number.

It is a junction number, because it is equal to n+sod(n) for n = 1981498 and 1981507.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 38081 + ... + 38132.

2^1981538 is an apocalyptic number.

1981538 is a deficient number, since it is larger than the sum of its proper divisors (1219450).

1981538 is a wasteful number, since it uses less digits than its factorization.

1981538 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76228.

The product of its digits is 8640, while the sum is 35.

The square root of 1981538 is about 1407.6711263644. The cubic root of 1981538 is about 125.6032282427.

The spelling of 1981538 in words is "one million, nine hundred eighty-one thousand, five hundred thirty-eight".