138644531 has 2 divisors, whose sum is σ = 138644532. Its totient is φ = 138644530.

The previous prime is 138644509. The next prime is 138644533. The reversal of 138644531 is 135446831.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 138644531 - 2²² = 134450227 is a prime.

It is a super-2 number, since 2×138644531² = 38444611952419922, which contains 22 as substring.

Together with 138644533, 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 = 138644491 and 138644500.

It is not a weakly prime, because it can be changed into another prime (138644533) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69322265 + 69322266.

It is an arithmetic number, because the mean of its divisors is an integer number (69322266).

Almost surely, 2^138644531 is an apocalyptic number.

138644531 is a deficient number, since it is larger than the sum of its proper divisors (1).

138644531 is an equidigital number, since it uses as much as digits as its factorization.

138644531 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 34560, while the sum is 35.

The square root of 138644531 is about 11774.7412285791. The cubic root of 138644531 is about 517.5681953273.

The spelling of 138644531 in words is "one hundred thirty-eight million, six hundred forty-four thousand, five hundred thirty-one".