31281881 has 4 divisors (see below), whose sum is σ = 31416372. Its totient is φ = 31147392.

The previous prime is 31281871. The next prime is 31281889. The reversal of 31281881 is 18818213.

It is a happy number.

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 2755600 + 28526281 = 1660^2 + 5341^2 .

It is a cyclic number.

It is not a de Polignac number, because 31281881 - 2¹⁴ = 31265497 is a prime.

It is a super-2 number, since 2×31281881² = 1957112157796322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31281889) 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, 66896 + ... + 67361.

It is an arithmetic number, because the mean of its divisors is an integer number (7854093).

Almost surely, 2^31281881 is an apocalyptic number.

It is an amenable number.

31281881 is a deficient number, since it is larger than the sum of its proper divisors (134491).

31281881 is a wasteful number, since it uses less digits than its factorization.

31281881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 134490.

The product of its digits is 3072, while the sum is 32.

The square root of 31281881 is about 5593.0207401725. The cubic root of 31281881 is about 315.0873395169.

The spelling of 31281881 in words is "thirty-one million, two hundred eighty-one thousand, eight hundred eighty-one".