1211100020021 has 4 divisors (see below), whose sum is σ = 1213750129932. Its totient is φ = 1208449910112.

The previous prime is 1211100019981. The next prime is 1211100020041. The reversal of 1211100020021 is 1200200011121.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1146387783025 + 64712236996 = 1070695^2 + 254386^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1211100020021 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1211100019984 and 1211100020011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1211100020041) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1325054270 + ... + 1325055183.

It is an arithmetic number, because the mean of its divisors is an integer number (303437532483).

Almost surely, 2^{1211100020021} is an apocalyptic number.

It is an amenable number.

1211100020021 is a deficient number, since it is larger than the sum of its proper divisors (2650109911).

1211100020021 is an equidigital number, since it uses as much as digits as its factorization.

1211100020021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2650109910.

The product of its (nonzero) digits is 8, while the sum is 11.

Adding to 1211100020021 its reverse (1200200011121), we get a palindrome (2411300031142).

The spelling of 1211100020021 in words is "one trillion, two hundred eleven billion, one hundred million, twenty thousand, twenty-one".