138437881 has 4 divisors (see below), whose sum is σ = 138519952. Its totient is φ = 138355812.

The previous prime is 138437867. The next prime is 138437899. The reversal of 138437881 is 188734831.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 188734831 = 103 ⋅1832377.

It is a cyclic number.

It is not a de Polignac number, because 138437881 - 2¹³ = 138429689 is a prime.

It is a super-2 number, since 2×138437881² = 38330093791540322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (138437801) 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 in 3 ways as a sum of consecutive naturals, for example, 38451 + ... + 41896.

It is an arithmetic number, because the mean of its divisors is an integer number (34629988).

Almost surely, 2^138437881 is an apocalyptic number.

It is an amenable number.

138437881 is a deficient number, since it is larger than the sum of its proper divisors (82071).

138437881 is an equidigital number, since it uses as much as digits as its factorization.

138437881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82070.

The product of its digits is 129024, while the sum is 43.

The square root of 138437881 is about 11765.9628165314. The cubic root of 138437881 is about 517.3109219247.

The spelling of 138437881 in words is "one hundred thirty-eight million, four hundred thirty-seven thousand, eight hundred eighty-one".