1221011020021 has 8 divisors (see below), whose sum is σ = 1314974324664. Its totient is φ = 1127053341120.

The previous prime is 1221011019997. The next prime is 1221011020027. The reversal of 1221011020021 is 1200201101221.

It can be written as a sum of positive squares in 4 ways, for example, as 19948455121 + 1201062564900 = 141239^2 + 1095930^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1221011020021 - 2¹¹ = 1221011017973 is a prime.

It is a super-2 number, since 2×1221011020021² (a number of 25 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (13).

It is a junction number, because it is equal to n+sod(n) for n = 1221011019983 and 1221011020010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221011020027) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 950170 + ... + 1828891.

It is an arithmetic number, because the mean of its divisors is an integer number (164371790583).

Almost surely, 2^{1221011020021} is an apocalyptic number.

It is an amenable number.

1221011020021 is a deficient number, since it is larger than the sum of its proper divisors (93963304643).

1221011020021 is a wasteful number, since it uses less digits than its factorization.

1221011020021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2812871.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 1221011020021 its reverse (1200201101221), we get a palindrome (2421212121242).

The spelling of 1221011020021 in words is "one trillion, two hundred twenty-one billion, eleven million, twenty thousand, twenty-one".