1221111020 has 24 divisors (see below), whose sum is σ = 2715177024. Its totient is φ = 459712256.

The previous prime is 1221111007. The next prime is 1221111029. The reversal of 1221111020 is 201111221.

It is a super-2 number, since 2×1221111020² = 2982224246330880800, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1221110992 and 1221111010.

It is not an unprimeable number, because it can be changed into a prime (1221111029) 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, 1795412 + ... + 1796091.

It is an arithmetic number, because the mean of its divisors is an integer number (113132376).

Almost surely, 2^1221111020 is an apocalyptic number.

1221111020 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221111020 is an abundant number, since it is smaller than the sum of its proper divisors (1494066004).

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

1221111020 is a wasteful number, since it uses less digits than its factorization.

1221111020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3591529 (or 3591527 counting only the distinct ones).

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

The square root of 1221111020 is about 34944.3989789494. The cubic root of 1221111020 is about 1068.8539918189.

Adding to 1221111020 its reverse (201111221), we get a palindrome (1422222241).

The spelling of 1221111020 in words is "one billion, two hundred twenty-one million, one hundred eleven thousand, twenty".