135205421 has 4 divisors (see below), whose sum is σ = 145605852. Its totient is φ = 124804992.

The previous prime is 135205393. The next prime is 135205429. The reversal of 135205421 is 124502531.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 124502531 = 131 ⋅950401.

It can be written as a sum of positive squares in 2 ways, for example, as 90516196 + 44689225 = 9514^2 + 6685^2 .

It is not a de Polignac number, because 135205421 - 2¹⁰ = 135204397 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 (135205429) 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, 5200196 + ... + 5200221.

It is an arithmetic number, because the mean of its divisors is an integer number (36401463).

Almost surely, 2^135205421 is an apocalyptic number.

It is an amenable number.

135205421 is a deficient number, since it is larger than the sum of its proper divisors (10400431).

135205421 is a wasteful number, since it uses less digits than its factorization.

135205421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10400430.

The product of its (nonzero) digits is 1200, while the sum is 23.

The square root of 135205421 is about 11627.7865907489. The cubic root of 135205421 is about 513.2528484130.

Adding to 135205421 its reverse (124502531), we get a palindrome (259707952).

The spelling of 135205421 in words is "one hundred thirty-five million, two hundred five thousand, four hundred twenty-one".