138126421 has 4 divisors (see below), whose sum is σ = 142582144. Its totient is φ = 133670700.

The previous prime is 138126419. The next prime is 138126437. The reversal of 138126421 is 124621831.

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: 124621831 = 331 ⋅376501.

It is a cyclic number.

It is not a de Polignac number, because 138126421 - 2¹ = 138126419 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 138126421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138126451) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2227815 + ... + 2227876.

It is an arithmetic number, because the mean of its divisors is an integer number (35645536).

Almost surely, 2^138126421 is an apocalyptic number.

It is an amenable number.

138126421 is a deficient number, since it is larger than the sum of its proper divisors (4455723).

138126421 is an equidigital number, since it uses as much as digits as its factorization.

138126421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4455722.

The product of its digits is 2304, while the sum is 28.

The square root of 138126421 is about 11752.7197277907. The cubic root of 138126421 is about 516.9226788579.

The spelling of 138126421 in words is "one hundred thirty-eight million, one hundred twenty-six thousand, four hundred twenty-one".