21011031121 has 4 divisors (see below), whose sum is σ = 21061177200. Its totient is φ = 20960885044.

The previous prime is 21011031103. The next prime is 21011031149. The reversal of 21011031121 is 12113011012.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21011031121 - 2¹¹ = 21011029073 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21011091121) 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, 25072411 + ... + 25073248.

It is an arithmetic number, because the mean of its divisors is an integer number (5265294300).

Almost surely, 2^21011031121 is an apocalyptic number.

It is an amenable number.

21011031121 is a deficient number, since it is larger than the sum of its proper divisors (50146079).

21011031121 is an equidigital number, since it uses as much as digits as its factorization.

21011031121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50146078.

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

Adding to 21011031121 its reverse (12113011012), we get a palindrome (33124042133).

The spelling of 21011031121 in words is "twenty-one billion, eleven million, thirty-one thousand, one hundred twenty-one".