9981997 has 4 divisors (see below), whose sum is σ = 10000476. Its totient is φ = 9963520.

The previous prime is 9981943. The next prime is 9982051. The reversal of 9981997 is 7991899.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7991899 = 733 ⋅10903.

It is an interprime number because it is at equal distance from previous prime (9981943) and next prime (9982051).

It can be written as a sum of positive squares in 2 ways, for example, as 427716 + 9554281 = 654^2 + 3091^2 .

It is a cyclic number.

It is not a de Polignac number, because 9981997 - 2⁷ = 9981869 is a prime.

It is a Duffinian number.

9981997 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9981197) 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, 8404 + ... + 9517.

It is an arithmetic number, because the mean of its divisors is an integer number (2500119).

Almost surely, 2^9981997 is an apocalyptic number.

It is an amenable number.

9981997 is a deficient number, since it is larger than the sum of its proper divisors (18479).

9981997 is a wasteful number, since it uses less digits than its factorization.

9981997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18478.

The product of its digits is 367416, while the sum is 52.

The square root of 9981997 is about 3159.4298536287. The cubic root of 9981997 is about 215.3141037142.

It can be divided in two parts, 998 and 1997, that multiplied together give a triangular number (1993006 = T₁₉₉₆).

The spelling of 9981997 in words is "nine million, nine hundred eighty-one thousand, nine hundred ninety-seven".