1221011020 has 24 divisors (see below), whose sum is σ = 2584318464. Its totient is φ = 484557696.

The previous prime is 1221010997. The next prime is 1221011021. The reversal of 1221011020 is 201101221.

It is a super-2 number, since 2×1221011020² = 2981735821922880800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a junction number, because it is equal to n+sod(n) for n = 1221010988 and 1221011006.

It is not an unprimeable number, because it can be changed into a prime (1221011021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 237817 + ... + 242896.

It is an arithmetic number, because the mean of its divisors is an integer number (107679936).

Almost surely, 2^1221011020 is an apocalyptic number.

1221011020 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221011020 is an abundant number, since it is smaller than the sum of its proper divisors (1363307444).

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

1221011020 is a wasteful number, since it uses less digits than its factorization.

1221011020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 480849 (or 480847 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 10.

The square root of 1221011020 is about 34942.9681051853. The cubic root of 1221011020 is about 1068.8248139322.

Adding to 1221011020 its reverse (201101221), we get a palindrome (1422112241).

The spelling of 1221011020 in words is "one billion, two hundred twenty-one million, eleven thousand, twenty".