2131211921 has 4 divisors (see below), whose sum is σ = 2131341492. Its totient is φ = 2131082352.

The previous prime is 2131211909. The next prime is 2131211933. The reversal of 2131211921 is 1291121312.

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

It is an interprime number because it is at equal distance from previous prime (2131211909) and next prime (2131211933).

It can be written as a sum of positive squares in 2 ways, for example, as 2046295696 + 84916225 = 45236^2 + 9215^2 .

It is a cyclic number.

It is not a de Polignac number, because 2131211921 - 2¹⁰ = 2131210897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2131211981) 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, 35786 + ... + 74451.

It is an arithmetic number, because the mean of its divisors is an integer number (532835373).

Almost surely, 2^2131211921 is an apocalyptic number.

It is an amenable number.

2131211921 is a deficient number, since it is larger than the sum of its proper divisors (129571).

2131211921 is a wasteful number, since it uses less digits than its factorization.

2131211921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129570.

The product of its digits is 216, while the sum is 23.

The square root of 2131211921 is about 46165.0508610139. The cubic root of 2131211921 is about 1286.8923293946.

It can be divided in two parts, 21312 and 11921, that added together give a palindrome (33233).

The spelling of 2131211921 in words is "two billion, one hundred thirty-one million, two hundred eleven thousand, nine hundred twenty-one".