138723885 has 24 divisors (see below), whose sum is σ = 242591544. Its totient is φ = 73328640.

The previous prime is 138723881. The next prime is 138723911. The reversal of 138723885 is 588327831.

It can be written as a sum of positive squares in 4 ways, for example, as 2604996 + 136118889 = 1614^2 + 11667^2 .

It is not a de Polignac number, because 138723885 - 2² = 138723881 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 138723885.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138723881) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 8556 + ... + 18725.

It is an arithmetic number, because the mean of its divisors is an integer number (10107981).

Almost surely, 2^138723885 is an apocalyptic number.

138723885 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

138723885 is a deficient number, since it is larger than the sum of its proper divisors (103867659).

138723885 is a wasteful number, since it uses less digits than its factorization.

138723885 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27405 (or 27402 counting only the distinct ones).

The product of its digits is 322560, while the sum is 45.

The square root of 138723885 is about 11778.1104172104. The cubic root of 138723885 is about 517.6669208787. Note that the first 3 decimals are identical.

The spelling of 138723885 in words is "one hundred thirty-eight million, seven hundred twenty-three thousand, eight hundred eighty-five".