135221551 has 4 divisors (see below), whose sum is σ = 135683352. Its totient is φ = 134759752.

The previous prime is 135221549. The next prime is 135221561. The reversal of 135221551 is 155122531.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 155122531 = 1489 ⋅104179.

It is a cyclic number.

It is not a de Polignac number, because 135221551 - 2¹ = 135221549 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 (135221501) 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, 230461 + ... + 231046.

It is an arithmetic number, because the mean of its divisors is an integer number (33920838).

Almost surely, 2^135221551 is an apocalyptic number.

135221551 is a deficient number, since it is larger than the sum of its proper divisors (461801).

135221551 is an equidigital number, since it uses as much as digits as its factorization.

135221551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 461800.

The product of its digits is 1500, while the sum is 25.

The square root of 135221551 is about 11628.4801672446. The cubic root of 135221551 is about 513.2732579478.

The spelling of 135221551 in words is "one hundred thirty-five million, two hundred twenty-one thousand, five hundred fifty-one".