9985981 has 4 divisors (see below), whose sum is σ = 9992764.
Its totient is φ = 9979200.
The previous prime is 9985973. The next prime is 9985993. The reversal of 9985981 is 1895899.
9985981 = 22342 + 22352.
It is a happy number.
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: 1895899 = 67 ⋅28297.
It can be written as a sum of positive squares in 2 ways, for example, as 4990756 + 4995225 = 2234^2 + 2235^2
It is a cyclic number.
It is not a de Polignac number, because 9985981 - 23 = 9985973 is a prime.
It is a super-2 number, since 2×99859812 = 199439633064722, which contains 22 as substring.
It is a Duffinian number.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (9985901) 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, 150 + ... + 4471.
It is an arithmetic number, because the mean of its divisors is an integer number (2498191).
Almost surely, 29985981 is an apocalyptic number.
9985981 is the 2235-th centered square number.
It is an amenable number.
9985981 is a deficient number, since it is larger than the sum of its proper divisors (6783).
9985981 is a wasteful number, since it uses less digits than its factorization.
9985981 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 6782.
The product of its digits is 233280, while the sum is 49.
The square root of 9985981 is about 3160.0602842351.
The cubic root of 9985981 is about 215.3427451872.
The spelling of 9985981 in words is "nine million, nine hundred eighty-five thousand, nine hundred eighty-one".