221221129 has 4 divisors (see below), whose sum is σ = 222213376. Its totient is φ = 220228884.

The previous prime is 221221127. The next prime is 221221213. The reversal of 221221129 is 921122122.

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: 921122122 = 2 ⋅460561061.

It is a cyclic number.

It is not a de Polignac number, because 221221129 - 2¹ = 221221127 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221221127) 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, 495789 + ... + 496234.

It is an arithmetic number, because the mean of its divisors is an integer number (55553344).

Almost surely, 2^221221129 is an apocalyptic number.

It is an amenable number.

221221129 is a deficient number, since it is larger than the sum of its proper divisors (992247).

221221129 is an equidigital number, since it uses as much as digits as its factorization.

221221129 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 992246.

The product of its digits is 288, while the sum is 22.

The square root of 221221129 is about 14873.5042609333. The cubic root of 221221129 is about 604.7959414722.

The spelling of 221221129 in words is "two hundred twenty-one million, two hundred twenty-one thousand, one hundred twenty-nine".