1211001220 has 48 divisors (see below), whose sum is σ = 2987707968. Its totient is φ = 406488960.

The previous prime is 1211001193. The next prime is 1211001223. The reversal of 1211001220 is 221001121.

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 = 1211001197 and 1211001206.

It is not an unprimeable number, because it can be changed into a prime (1211001223) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 208854 + ... + 214573.

It is an arithmetic number, because the mean of its divisors is an integer number (62243916).

Almost surely, 2^1211001220 is an apocalyptic number.

1211001220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1211001220 is an abundant number, since it is smaller than the sum of its proper divisors (1776706748).

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

1211001220 is a wasteful number, since it uses less digits than its factorization.

1211001220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 423460 (or 423458 counting only the distinct ones).

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

The square root of 1211001220 is about 34799.4428116313. The cubic root of 1211001220 is about 1065.8960682089.

Adding to 1211001220 its reverse (221001121), we get a palindrome (1432002341).

Subtracting from 1211001220 its reverse (221001121), we obtain a palindrome (990000099).

The spelling of 1211001220 in words is "one billion, two hundred eleven million, one thousand, two hundred twenty".