1001211220 has 12 divisors (see below), whose sum is σ = 2102543604. Its totient is φ = 400484480.

The previous prime is 1001211203. The next prime is 1001211221. The reversal of 1001211220 is 221121001.

It can be written as a sum of positive squares in 2 ways, for example, as 339075396 + 662135824 = 18414^2 + 25732^2 .

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 = 1001211197 and 1001211206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1001211221) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25030261 + ... + 25030300.

It is an arithmetic number, because the mean of its divisors is an integer number (175211967).

Almost surely, 2^1001211220 is an apocalyptic number.

1001211220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1001211220 is an abundant number, since it is smaller than the sum of its proper divisors (1101332384).

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

1001211220 is a wasteful number, since it uses less digits than its factorization.

1001211220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50060570 (or 50060568 counting only the distinct ones).

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

The square root of 1001211220 is about 31641.9218758912. The cubic root of 1001211220 is about 1000.4035771036.

Adding to 1001211220 its reverse (221121001), we get a palindrome (1222332221).

The spelling of 1001211220 in words is "one billion, one million, two hundred eleven thousand, two hundred twenty".