138243893 has 4 divisors (see below), whose sum is σ = 139536000. Its totient is φ = 136951788.

The previous prime is 138243863. The next prime is 138243901. The reversal of 138243893 is 398342831.

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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-138243893 is a prime.

It is a super-2 number, since 2×138243893² = 38222747903590898, which contains 22 as substring.

It is a Duffinian number.

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 138243893.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138243863) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 645893 + ... + 646106.

It is an arithmetic number, because the mean of its divisors is an integer number (34884000).

Almost surely, 2^138243893 is an apocalyptic number.

It is an amenable number.

138243893 is a deficient number, since it is larger than the sum of its proper divisors (1292107).

138243893 is a wasteful number, since it uses less digits than its factorization.

138243893 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1292106.

The product of its digits is 124416, while the sum is 41.

The square root of 138243893 is about 11757.7163173807. The cubic root of 138243893 is about 517.0691792740.

The spelling of 138243893 in words is "one hundred thirty-eight million, two hundred forty-three thousand, eight hundred ninety-three".