31211221121 has 4 divisors (see below), whose sum is σ = 31299638532. Its totient is φ = 31122803712.

The previous prime is 31211221103. The next prime is 31211221183. The reversal of 31211221121 is 12112211213.

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 12535265521 + 18675955600 = 111961^2 + 136660^2 .

It is a cyclic number.

It is not a de Polignac number, because 31211221121 - 2¹⁴ = 31211204737 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 31211221121.

It is not an unprimeable number, because it can be changed into a prime (31211211121) 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, 44208176 + ... + 44208881.

It is an arithmetic number, because the mean of its divisors is an integer number (7824909633).

Almost surely, 2^31211221121 is an apocalyptic number.

It is an amenable number.

31211221121 is a deficient number, since it is larger than the sum of its proper divisors (88417411).

31211221121 is an equidigital number, since it uses as much as digits as its factorization.

31211221121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88417410.

The product of its digits is 48, while the sum is 17.

Adding to 31211221121 its reverse (12112211213), we get a palindrome (43323432334).

It can be divided in two parts, 3 and 1211221121, that multiplied together give a palindrome (3633663363).

The spelling of 31211221121 in words is "thirty-one billion, two hundred eleven million, two hundred twenty-one thousand, one hundred twenty-one".