31945139 has 2 divisors, whose sum is σ = 31945140. Its totient is φ = 31945138.

The previous prime is 31945073. The next prime is 31945157. The reversal of 31945139 is 93154913.

It is a strong prime.

It is an emirp because it is prime and its reverse (93154913) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31945139 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 31945099 and 31945108.

It is not a weakly prime, because it can be changed into another prime (31945339) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15972569 + 15972570.

It is an arithmetic number, because the mean of its divisors is an integer number (15972570).

Almost surely, 2^31945139 is an apocalyptic number.

31945139 is a deficient number, since it is larger than the sum of its proper divisors (1).

31945139 is an equidigital number, since it uses as much as digits as its factorization.

31945139 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14580, while the sum is 35.

The square root of 31945139 is about 5652.0030962483. The cubic root of 31945139 is about 317.2986765942.

Subtracting from 31945139 its sum of digits (35), we obtain a square (31945104 = 5652²).

It can be divided in two parts, 319 and 45139, that multiplied together give a palindrome (14399341).

The spelling of 31945139 in words is "thirty-one million, nine hundred forty-five thousand, one hundred thirty-nine".