9131981 has 4 divisors (see below), whose sum is σ = 9167772. Its totient is φ = 9096192.

The previous prime is 9131977. The next prime is 9131987. The reversal of 9131981 is 1891319.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 4990756 + 4141225 = 2234^2 + 2035^2 .

It is a cyclic number.

It is not a de Polignac number, because 9131981 - 2² = 9131977 is a prime.

It is a super-2 number, since 2×9131981² = 166786153968722, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9131987) 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, 17510 + ... + 18023.

It is an arithmetic number, because the mean of its divisors is an integer number (2291943).

Almost surely, 2^9131981 is an apocalyptic number.

It is an amenable number.

9131981 is a deficient number, since it is larger than the sum of its proper divisors (35791).

9131981 is a wasteful number, since it uses less digits than its factorization.

9131981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35790.

The product of its digits is 1944, while the sum is 32.

The square root of 9131981 is about 3021.9167758229. The cubic root of 9131981 is about 209.0202356726.

The spelling of 9131981 in words is "nine million, one hundred thirty-one thousand, nine hundred eighty-one".