1211131021 has 4 divisors (see below), whose sum is σ = 1240670844. Its totient is φ = 1181591200.

The previous prime is 1211131013. The next prime is 1211131049. The reversal of 1211131021 is 1201311121.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 438902500 + 772228521 = 20950^2 + 27789^2 .

It is a cyclic number.

It is not a de Polignac number, because 1211131021 - 2³ = 1211131013 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1211130992 and 1211131010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1211131001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14769850 + ... + 14769931.

It is an arithmetic number, because the mean of its divisors is an integer number (310167711).

Almost surely, 2^1211131021 is an apocalyptic number.

It is an amenable number.

1211131021 is a deficient number, since it is larger than the sum of its proper divisors (29539823).

1211131021 is an equidigital number, since it uses as much as digits as its factorization.

1211131021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29539822.

The product of its (nonzero) digits is 12, while the sum is 13.

The square root of 1211131021 is about 34801.3077484166. The cubic root of 1211131021 is about 1065.9341494898.

Adding to 1211131021 its reverse (1201311121), we get a palindrome (2412442142).

The spelling of 1211131021 in words is "one billion, two hundred eleven million, one hundred thirty-one thousand, twenty-one".