221012121 has 16 divisors (see below), whose sum is σ = 340383168. Its totient is φ = 126067200.

The previous prime is 221012119. The next prime is 221012149. The reversal of 221012121 is 121210122.

It is not a de Polignac number, because 221012121 - 2¹ = 221012119 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 221012097 and 221012106.

It is not an unprimeable number, because it can be changed into a prime (221012111) 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, 196420 + ... + 197541.

It is an arithmetic number, because the mean of its divisors is an integer number (21273948).

Almost surely, 2^221012121 is an apocalyptic number.

It is an amenable number.

221012121 is a deficient number, since it is larger than the sum of its proper divisors (119371047).

221012121 is a wasteful number, since it uses less digits than its factorization.

221012121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 393992.

The product of its (nonzero) digits is 16, while the sum is 12.

The square root of 221012121 is about 14866.4764150756. The cubic root of 221012121 is about 604.6054126243.

Adding to 221012121 its reverse (121210122), we get a palindrome (342222243).

The spelling of 221012121 in words is "two hundred twenty-one million, twelve thousand, one hundred twenty-one".