1211221120021 has 18 divisors (see below), whose sum is σ = 1391743455830. Its totient is φ = 1053235700880.

The previous prime is 1211221120007. The next prime is 1211221120033. The reversal of 1211221120021 is 1200211221121.

It can be written as a sum of positive squares in only one way, i.e., 1211210302500 + 10817521 = 1100550^2 + 3289^2 .

It is not a de Polignac number, because 1211221120021 - 2¹³ = 1211221111829 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1211221119977 and 1211221120004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1211221120061) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 9397326 + ... + 9525343.

Almost surely, 2^{1211221120021} is an apocalyptic number.

1211221120021 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1211221120021 is a deficient number, since it is larger than the sum of its proper divisors (180522335809).

1211221120021 is a wasteful number, since it uses less digits than its factorization.

1211221120021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18922737 (or 18922703 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 16.

Adding to 1211221120021 its reverse (1200211221121), we get a palindrome (2411432341142).

The spelling of 1211221120021 in words is "one trillion, two hundred eleven billion, two hundred twenty-one million, one hundred twenty thousand, twenty-one".