135555221 has 4 divisors (see below), whose sum is σ = 138707712. Its totient is φ = 132402732.

The previous prime is 135555181. The next prime is 135555247. The reversal of 135555221 is 122555531.

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: 122555531 = 7 ⋅17507933.

It is a cyclic number.

It is not a de Polignac number, because 135555221 - 2¹⁰ = 135554197 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 (135555521) 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, 1576181 + ... + 1576266.

It is an arithmetic number, because the mean of its divisors is an integer number (34676928).

Almost surely, 2^135555221 is an apocalyptic number.

It is an amenable number.

135555221 is a deficient number, since it is larger than the sum of its proper divisors (3152491).

135555221 is an equidigital number, since it uses as much as digits as its factorization.

135555221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3152490.

The product of its digits is 7500, while the sum is 29.

The square root of 135555221 is about 11642.8184302599. The cubic root of 135555221 is about 513.6950921165.

The spelling of 135555221 in words is "one hundred thirty-five million, five hundred fifty-five thousand, two hundred twenty-one".