1221111211020 has 96 divisors (see below), whose sum is σ = 3504451399680. Its totient is φ = 317527257600.

The previous prime is 1221111211013. The next prime is 1221111211027. The reversal of 1221111211020 is 201121111221.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (1221111211013) and next prime (1221111211027).

It is a super-2 number, since 2×1221111211020² (a number of 25 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is not an unprimeable number, because it can be changed into a prime (1221111211027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1156821 + ... + 1944339.

It is an arithmetic number, because the mean of its divisors is an integer number (36504702080).

Almost surely, 2^{1221111211020} is an apocalyptic number.

1221111211020 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1221111211020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1752225699840).

1221111211020 is an abundant number, since it is smaller than the sum of its proper divisors (2283340188660).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1221111211020 is a wasteful number, since it uses less digits than its factorization.

1221111211020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 788175 (or 788173 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 15.

Adding to 1221111211020 its reverse (201121111221), we get a palindrome (1422232322241).

The spelling of 1221111211020 in words is "one trillion, two hundred twenty-one billion, one hundred eleven million, two hundred eleven thousand, twenty".