1221110001220 has 24 divisors (see below), whose sum is σ = 2564390455704. Its totient is φ = 488432676096.

The previous prime is 1221110001197. The next prime is 1221110001253. The reversal of 1221110001220 is 221000111221.

It can be written as a sum of positive squares in 4 ways, for example, as 186625728004 + 1034484273216 = 432002^2 + 1017096^2 .

It is a super-2 number, since 2×1221110001220² (a number of 25 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1221110001220.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 205152 + ... + 1576168.

It is an arithmetic number, because the mean of its divisors is an integer number (106849602321).

Almost surely, 2^{1221110001220} is an apocalyptic number.

1221110001220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221110001220 is an abundant number, since it is smaller than the sum of its proper divisors (1343280454484).

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

1221110001220 is a wasteful number, since it uses less digits than its factorization.

1221110001220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1415559 (or 1415557 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 1221110001220 its reverse (221000111221), we get a palindrome (1442110112441).

The spelling of 1221110001220 in words is "one trillion, two hundred twenty-one billion, one hundred ten million, one thousand, two hundred twenty".