31781413 has 2 divisors, whose sum is σ = 31781414. Its totient is φ = 31781412.

The previous prime is 31781411. The next prime is 31781441. The reversal of 31781413 is 31418713.

It is the 2302-nd star number.

It is an a-pointer prime, because the next prime (31781441) can be obtained adding 31781413 to its sum of digits (28).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 31169889 + 611524 = 5583^2 + 782^2 .

It is a cyclic number.

It is not a de Polignac number, because 31781413 - 2¹ = 31781411 is a prime.

Together with 31781411, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31781411) 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 as a sum of consecutive naturals, namely, 15890706 + 15890707.

It is an arithmetic number, because the mean of its divisors is an integer number (15890707).

Almost surely, 2^31781413 is an apocalyptic number.

It is an amenable number.

31781413 is a deficient number, since it is larger than the sum of its proper divisors (1).

31781413 is an equidigital number, since it uses as much as digits as its factorization.

31781413 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2016, while the sum is 28.

The square root of 31781413 is about 5637.5005986696. The cubic root of 31781413 is about 316.7556722415.

The spelling of 31781413 in words is "thirty-one million, seven hundred eighty-one thousand, four hundred thirteen".