135521440221 has 16 divisors (see below), whose sum is σ = 187865189568. Its totient is φ = 86828438400.

The previous prime is 135521440181. The next prime is 135521440231. The reversal of 135521440221 is 122044125531.

It is not a de Polignac number, because 135521440221 - 2¹⁰ = 135521439197 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (135521440231) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8214150 + ... + 8230631.

It is an arithmetic number, because the mean of its divisors is an integer number (11741574348).

Almost surely, 2^135521440221 is an apocalyptic number.

It is an amenable number.

135521440221 is a deficient number, since it is larger than the sum of its proper divisors (52343749347).

135521440221 is a wasteful number, since it uses less digits than its factorization.

135521440221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16444892.

The product of its (nonzero) digits is 9600, while the sum is 30.

Adding to 135521440221 its reverse (122044125531), we get a palindrome (257565565752).

The spelling of 135521440221 in words is "one hundred thirty-five billion, five hundred twenty-one million, four hundred forty thousand, two hundred twenty-one".