138931031 has 2 divisors, whose sum is σ = 138931032. Its totient is φ = 138931030.

The previous prime is 138931019. The next prime is 138931033. The reversal of 138931031 is 130139831.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 138931031 - 2¹⁰ = 138930007 is a prime.

It is a super-3 number, since 3×138931031³ (a number of 25 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

Together with 138931033, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 138930985 and 138931003.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (138931033) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69465515 + 69465516.

It is an arithmetic number, because the mean of its divisors is an integer number (69465516).

Almost surely, 2^138931031 is an apocalyptic number.

138931031 is a deficient number, since it is larger than the sum of its proper divisors (1).

138931031 is an equidigital number, since it uses as much as digits as its factorization.

138931031 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1944, while the sum is 29.

The square root of 138931031 is about 11786.9008225233. The cubic root of 138931031 is about 517.9244571640.

The spelling of 138931031 in words is "one hundred thirty-eight million, nine hundred thirty-one thousand, thirty-one".