135243121421 has 4 divisors (see below), whose sum is σ = 135348864000. Its totient is φ = 135137378844.

The previous prime is 135243121369. The next prime is 135243121423. The reversal of 135243121421 is 124121342531.

It is a happy number.

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 not a de Polignac number, because 135243121421 - 2¹⁸ = 135242859277 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (135243121423) 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, 52869371 + ... + 52871928.

It is an arithmetic number, because the mean of its divisors is an integer number (33837216000).

Almost surely, 2^135243121421 is an apocalyptic number.

It is an amenable number.

135243121421 is a deficient number, since it is larger than the sum of its proper divisors (105742579).

135243121421 is a wasteful number, since it uses less digits than its factorization.

135243121421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 105742578.

The product of its digits is 5760, while the sum is 29.

Adding to 135243121421 its reverse (124121342531), we get a palindrome (259364463952).

The spelling of 135243121421 in words is "one hundred thirty-five billion, two hundred forty-three million, one hundred twenty-one thousand, four hundred twenty-one".