31991149 has 4 divisors (see below), whose sum is σ = 32003100. Its totient is φ = 31979200.

The previous prime is 31991143. The next prime is 31991153. The reversal of 31991149 is 94119913.

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: 94119913 = 401 ⋅234713.

It can be written as a sum of positive squares in 2 ways, for example, as 14768649 + 17222500 = 3843^2 + 4150^2 .

It is a cyclic number.

It is not a de Polignac number, because 31991149 - 2¹¹ = 31989101 is a prime.

It is a super-2 number, since 2×31991149² = 2046867228680402, 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 (31991143) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 99 + ... + 7999.

It is an arithmetic number, because the mean of its divisors is an integer number (8000775).

Almost surely, 2^31991149 is an apocalyptic number.

It is an amenable number.

31991149 is a deficient number, since it is larger than the sum of its proper divisors (11951).

31991149 is an equidigital number, since it uses as much as digits as its factorization.

31991149 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11950.

The product of its digits is 8748, while the sum is 37.

The square root of 31991149 is about 5656.0718701233. The cubic root of 31991149 is about 317.4509366805.

The spelling of 31991149 in words is "thirty-one million, nine hundred ninety-one thousand, one hundred forty-nine".