1221220120021 has 16 divisors (see below), whose sum is σ = 1428817631040. Its totient is φ = 1031923825920.

The previous prime is 1221220119997. The next prime is 1221220120027. The reversal of 1221220120021 is 1200210221221.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 1221220120021 - 2¹⁹ = 1221219595733 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1221220119977 and 1221220120004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221220120027) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 55113060 + ... + 55135213.

It is an arithmetic number, because the mean of its divisors is an integer number (89301101940).

Almost surely, 2^{1221220120021} is an apocalyptic number.

1221220120021 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1221220120021 is a deficient number, since it is larger than the sum of its proper divisors (207597511019).

1221220120021 is a wasteful number, since it uses less digits than its factorization.

1221220120021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110248356.

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 1221220120021 its reverse (1200210221221), we get a palindrome (2421430341242).

The spelling of 1221220120021 in words is "one trillion, two hundred twenty-one billion, two hundred twenty million, one hundred twenty thousand, twenty-one".