2101312121 has 4 divisors (see below), whose sum is σ = 2103395700. Its totient is φ = 2099228544.

The previous prime is 2101312111. The next prime is 2101312127. The reversal of 2101312121 is 1212131012.

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 1084977721 + 1016334400 = 32939^2 + 31880^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2101312121 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2101312096 and 2101312105.

It is not an unprimeable number, because it can be changed into a prime (2101312127) 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, 1040276 + ... + 1042293.

It is an arithmetic number, because the mean of its divisors is an integer number (525848925).

Almost surely, 2^2101312121 is an apocalyptic number.

It is an amenable number.

2101312121 is a deficient number, since it is larger than the sum of its proper divisors (2083579).

2101312121 is a wasteful number, since it uses less digits than its factorization.

2101312121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2083578.

The product of its (nonzero) digits is 24, while the sum is 14.

The square root of 2101312121 is about 45840.0711277808. The cubic root of 2101312121 is about 1280.8458197462.

Adding to 2101312121 its reverse (1212131012), we get a palindrome (3313443133).

The spelling of 2101312121 in words is "two billion, one hundred one million, three hundred twelve thousand, one hundred twenty-one".