1221210121221 has 72 divisors (see below), whose sum is σ = 1866780167616. Its totient is φ = 769165985280.

The previous prime is 1221210121199. The next prime is 1221210121231.

1221210121221 is a `hidden beast` number, since 1 + 221 + 210 + 1 + 212 + 21 = 666.

1221210121221 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 1221210121221 - 2¹⁴ = 1221210104837 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1221210121194 and 1221210121203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221210121231) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 179824336 + ... + 179831126.

It is an arithmetic number, because the mean of its divisors is an integer number (25927502328).

Almost surely, 2^{1221210121221} is an apocalyptic number.

It is an amenable number.

1221210121221 is a deficient number, since it is larger than the sum of its proper divisors (645570046395).

1221210121221 is a wasteful number, since it uses less digits than its factorization.

1221210121221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7303 (or 7277 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 18.

It can be divided in two parts, 1221210 and 121221, that added together give a palindrome (1342431).

The spelling of 1221210121221 in words is "one trillion, two hundred twenty-one billion, two hundred ten million, one hundred twenty-one thousand, two hundred twenty-one".