1981575 has 18 divisors (see below), whose sum is σ = 3549624. Its totient is φ = 1056720.

The previous prime is 1981547. The next prime is 1981583. The reversal of 1981575 is 5751891.

1981575 is a `hidden beast` number, since 1 + 9 + 81 + 575 = 666.

It is not a de Polignac number, because 1981575 - 2⁵ = 1981543 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 4179 + ... + 4628.

2^1981575 is an apocalyptic number.

1981575 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1981575 is a deficient number, since it is larger than the sum of its proper divisors (1568049).

1981575 is a wasteful number, since it uses less digits than its factorization.

1981575 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8823 (or 8815 counting only the distinct ones).

The product of its digits is 12600, while the sum is 36.

The square root of 1981575 is about 1407.6842685773. The cubic root of 1981575 is about 125.6040100076.

It can be divided in two parts, 1981 and 575, that added together give a triangular number (2556 = T₇₁).

The spelling of 1981575 in words is "one million, nine hundred eighty-one thousand, five hundred seventy-five".