1211220021220 has 36 divisors (see below), whose sum is σ = 2795816137212. Its totient is φ = 440443643200.

The previous prime is 1211220021157. The next prime is 1211220021251. The reversal of 1211220021220 is 221200221121.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 785552506596 + 425667514624 = 886314^2 + 652432^2 .

It is a junction number, because it is equal to n+sod(n) for n = 1211220021194 and 1211220021203.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 250249651 + ... + 250254490.

It is an arithmetic number, because the mean of its divisors is an integer number (77661559367).

Almost surely, 2^{1211220021220} is an apocalyptic number.

1211220021220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1211220021220 is an abundant number, since it is smaller than the sum of its proper divisors (1584596115992).

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

1211220021220 is a wasteful number, since it uses less digits than its factorization.

1211220021220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 500504172 (or 500504159 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 1211220021220 its reverse (221200221121), we get a palindrome (1432420242341).

The spelling of 1211220021220 in words is "one trillion, two hundred eleven billion, two hundred twenty million, twenty-one thousand, two hundred twenty".