31242139 has 2 divisors, whose sum is σ = 31242140. Its totient is φ = 31242138.

The previous prime is 31242109. The next prime is 31242143. The reversal of 31242139 is 93124213.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 31242139 - 2⁹ = 31241627 is a prime.

It is not a weakly prime, because it can be changed into another prime (31242109) 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, 15621069 + 15621070.

It is an arithmetic number, because the mean of its divisors is an integer number (15621070).

Almost surely, 2^31242139 is an apocalyptic number.

31242139 is a deficient number, since it is larger than the sum of its proper divisors (1).

31242139 is an equidigital number, since it uses as much as digits as its factorization.

31242139 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1296, while the sum is 25.

The square root of 31242139 is about 5589.4667903119. The cubic root of 31242139 is about 314.9538489538.

The spelling of 31242139 in words is "thirty-one million, two hundred forty-two thousand, one hundred thirty-nine".