1221200111021 has 6 divisors (see below), whose sum is σ = 1342310865966. Its totient is φ = 1110181919000.

The previous prime is 1221200111003. The next prime is 1221200111051. The reversal of 1221200111021 is 1201110021221.

It can be written as a sum of positive squares in only one way, i.e., 1219092015625 + 2108095396 = 1104125^2 + 45914^2 .

It is a de Polignac number, because none of the positive numbers 2^k-1221200111021 is a prime.

It is a super-2 number, since 2×1221200111021² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1221200110987 and 1221200111005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221200111051) 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, 5046281330 + ... + 5046281571.

It is an arithmetic number, because the mean of its divisors is an integer number (223718477661).

Almost surely, 2^{1221200111021} is an apocalyptic number.

1221200111021 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1221200111021 is a deficient number, since it is larger than the sum of its proper divisors (121110754945).

1221200111021 is a wasteful number, since it uses less digits than its factorization.

1221200111021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10092562923 (or 10092562912 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 1221200111021 its reverse (1201110021221), we get a palindrome (2422310132242).

The spelling of 1221200111021 in words is "one trillion, two hundred twenty-one billion, two hundred million, one hundred eleven thousand, twenty-one".