31398181 has 2 divisors, whose sum is σ = 31398182. Its totient is φ = 31398180.

The previous prime is 31398149. The next prime is 31398217. The reversal of 31398181 is 18189313.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 23184225 + 8213956 = 4815^2 + 2866^2 .

It is an emirp because it is prime and its reverse (18189313) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31398181 - 2⁵ = 31398149 is a prime.

It is a super-2 number, since 2×31398181² = 1971691540217522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31398131) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15699090 + 15699091.

It is an arithmetic number, because the mean of its divisors is an integer number (15699091).

Almost surely, 2^31398181 is an apocalyptic number.

It is an amenable number.

31398181 is a deficient number, since it is larger than the sum of its proper divisors (1).

31398181 is an equidigital number, since it uses as much as digits as its factorization.

31398181 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5184, while the sum is 34.

The square root of 31398181 is about 5603.4079808631. The cubic root of 31398181 is about 315.4773345917.

The spelling of 31398181 in words is "thirty-one million, three hundred ninety-eight thousand, one hundred eighty-one".