1985681 has 4 divisors (see below), whose sum is σ = 1988532. Its totient is φ = 1982832.

The previous prime is 1985677. The next prime is 1985689. The reversal of 1985681 is 1865891.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1865891 = 167 ⋅11173.

It can be written as a sum of positive squares in 2 ways, for example, as 70225 + 1915456 = 265^2 + 1384^2 .

It is a cyclic number.

It is not a de Polignac number, because 1985681 - 2² = 1985677 is a prime.

It is a super-2 number, since 2×1985681² = 7885858067522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1985689) 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, 395 + ... + 2031.

It is an arithmetic number, because the mean of its divisors is an integer number (497133).

2^1985681 is an apocalyptic number.

It is an amenable number.

1985681 is a deficient number, since it is larger than the sum of its proper divisors (2851).

1985681 is a wasteful number, since it uses less digits than its factorization.

1985681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2850.

The product of its digits is 17280, while the sum is 38.

The square root of 1985681 is about 1409.1419374925. The cubic root of 1985681 is about 125.6907043899.

The spelling of 1985681 in words is "one million, nine hundred eighty-five thousand, six hundred eighty-one".