20211221111121 has 6 divisors (see below), whose sum is σ = 29193986049410. Its totient is φ = 13474147407408.

The previous prime is 20211221111117. The next prime is 20211221111141. The reversal of 20211221111121 is 12111112211202.

It is a happy number.

20211221111121 is a `hidden beast` number, since 2 + 0 + 211 + 221 + 111 + 121 = 666.

It can be written as a sum of positive squares in only one way, i.e., 17733666410496 + 2477554700625 = 4211136^2 + 1574025^2 .

It is not a de Polignac number, because 20211221111121 - 2² = 20211221111117 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20211221111094 and 20211221111103.

It is not an unprimeable number, because it can be changed into a prime (20211221111101) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1122845617276 + ... + 1122845617293.

Almost surely, 2^{20211221111121} is an apocalyptic number.

It is an amenable number.

20211221111121 is a deficient number, since it is larger than the sum of its proper divisors (8982764938289).

20211221111121 is a wasteful number, since it uses less digits than its factorization.

20211221111121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2245691234575 (or 2245691234572 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 18.

Adding to 20211221111121 its reverse (12111112211202), we get a palindrome (32322333322323).

The spelling of 20211221111121 in words is "twenty trillion, two hundred eleven billion, two hundred twenty-one million, one hundred eleven thousand, one hundred twenty-one".