1221111221220 has 72 divisors (see below), whose sum is σ = 4040768047680. Its totient is φ = 296026962240.

The previous prime is 1221111221219. The next prime is 1221111221273. The reversal of 1221111221220 is 221221111221.

1221111221220 is a `hidden beast` number, since 1 + 2 + 211 + 11 + 221 + 220 = 666.

It is a super-3 number, since 3×1221111221220³ (a number of 37 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 1221111221193 and 1221111221202.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 308359440 + ... + 308363399.

It is an arithmetic number, because the mean of its divisors is an integer number (56121778440).

Almost surely, 2^{1221111221220} is an apocalyptic number.

1221111221220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221111221220 is an abundant number, since it is smaller than the sum of its proper divisors (2819656826460).

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

1221111221220 is a wasteful number, since it uses less digits than its factorization.

1221111221220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 616722865 (or 616722860 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 18.

Adding to 1221111221220 its reverse (221221111221), we get a palindrome (1442332332441).

The spelling of 1221111221220 in words is "one trillion, two hundred twenty-one billion, one hundred eleven million, two hundred twenty-one thousand, two hundred twenty".