155445603426221 has 4 divisors (see below), whose sum is σ = 159646835951292. Its totient is φ = 151244370901152.

The previous prime is 155445603426161. The next prime is 155445603426233. The reversal of 155445603426221 is 122624306544551.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 88031568960196 + 67414034466025 = 9382514^2 + 8210605^2 .

It is a cyclic number.

It is not a de Polignac number, because 155445603426221 - 2³⁴ = 155428423557037 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 155445603426221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (155445603423221) 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, 2100616262480 + ... + 2100616262553.

It is an arithmetic number, because the mean of its divisors is an integer number (39911708987823).

Almost surely, 2^{155445603426221} is an apocalyptic number.

It is an amenable number.

155445603426221 is a deficient number, since it is larger than the sum of its proper divisors (4201232525071).

155445603426221 is an equidigital number, since it uses as much as digits as its factorization.

155445603426221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4201232525070.

The product of its (nonzero) digits is 6912000, while the sum is 50.

The spelling of 155445603426221 in words is "one hundred fifty-five trillion, four hundred forty-five billion, six hundred three million, four hundred twenty-six thousand, two hundred twenty-one".