31431481 has 2 divisors, whose sum is σ = 31431482. Its totient is φ = 31431480.

The previous prime is 31431479. The next prime is 31431497. The reversal of 31431481 is 18413413.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 30074256 + 1357225 = 5484^2 + 1165^2 .

It is a cyclic number.

It is not a de Polignac number, because 31431481 - 2¹ = 31431479 is a prime.

It is a super-2 number, since 2×31431481² = 1975875995706722, which contains 22 as substring.

Together with 31431479, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (31431451) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15715740 + 15715741.

It is an arithmetic number, because the mean of its divisors is an integer number (15715741).

Almost surely, 2^31431481 is an apocalyptic number.

It is an amenable number.

31431481 is a deficient number, since it is larger than the sum of its proper divisors (1).

31431481 is an equidigital number, since it uses as much as digits as its factorization.

31431481 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1152, while the sum is 25.

The square root of 31431481 is about 5606.3785994169. The cubic root of 31431481 is about 315.5888238902.

Adding to 31431481 its reverse (18413413), we get a palindrome (49844894).

It can be divided in two parts, 3143 and 1481, that added together give a square (4624 = 68²).

The spelling of 31431481 in words is "thirty-one million, four hundred thirty-one thousand, four hundred eighty-one".