221550121551 has 16 divisors (see below), whose sum is σ = 330964311168. Its totient is φ = 130643805600.

The previous prime is 221550121511. The next prime is 221550121571. The reversal of 221550121551 is 155121055122.

It is not a de Polignac number, because 221550121551 - 2¹⁹ = 221549597263 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221550121511) 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, 90723645 + ... + 90726086.

It is an arithmetic number, because the mean of its divisors is an integer number (20685269448).

Almost surely, 2^221550121551 is an apocalyptic number.

221550121551 is a deficient number, since it is larger than the sum of its proper divisors (109414189617).

221550121551 is a wasteful number, since it uses less digits than its factorization.

221550121551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 181449782.

The product of its (nonzero) digits is 5000, while the sum is 30.

Adding to 221550121551 its reverse (155121055122), we get a palindrome (376671176673).

The spelling of 221550121551 in words is "two hundred twenty-one billion, five hundred fifty million, one hundred twenty-one thousand, five hundred fifty-one".