138723881 has 2 divisors, whose sum is σ = 138723882. Its totient is φ = 138723880.

The previous prime is 138723877. The next prime is 138723911. The reversal of 138723881 is 188327831.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 93296281 + 45427600 = 9659^2 + 6740^2 .

It is a cyclic number.

It is not a de Polignac number, because 138723881 - 2² = 138723877 is a prime.

It is a super-2 number, since 2×138723881² = 38488630319404322, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (138723811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69361940 + 69361941.

It is an arithmetic number, because the mean of its divisors is an integer number (69361941).

Almost surely, 2^138723881 is an apocalyptic number.

It is an amenable number.

138723881 is a deficient number, since it is larger than the sum of its proper divisors (1).

138723881 is an equidigital number, since it uses as much as digits as its factorization.

138723881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 64512, while the sum is 41.

The square root of 138723881 is about 11778.1102474039. The cubic root of 138723881 is about 517.6669159032. Note that the first 3 decimals are identical.

The spelling of 138723881 in words is "one hundred thirty-eight million, seven hundred twenty-three thousand, eight hundred eighty-one".