221836121 has 4 divisors (see below), whose sum is σ = 238900452. Its totient is φ = 204771792.

The previous prime is 221836103. The next prime is 221836141. The reversal of 221836121 is 121638122.

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 47886400 + 173949721 = 6920^2 + 13189^2 .

It is a cyclic number.

It is not a de Polignac number, because 221836121 - 2²⁶ = 154727257 is a prime.

It is a super-2 number, since 2×221836121² = 98422529160653282, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221836141) 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, 8532146 + ... + 8532171.

It is an arithmetic number, because the mean of its divisors is an integer number (59725113).

Almost surely, 2^221836121 is an apocalyptic number.

It is an amenable number.

221836121 is a deficient number, since it is larger than the sum of its proper divisors (17064331).

221836121 is a wasteful number, since it uses less digits than its factorization.

221836121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17064330.

The product of its digits is 1152, while the sum is 26.

The square root of 221836121 is about 14894.1639913088. The cubic root of 221836121 is about 605.3558646759.

The spelling of 221836121 in words is "two hundred twenty-one million, eight hundred thirty-six thousand, one hundred twenty-one".