21121121011 has 4 divisors (see below), whose sum is σ = 22363539912. Its totient is φ = 19878702112.

The previous prime is 21121120987. The next prime is 21121121039. The reversal of 21121121011 is 11012112112.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21121121011 - 2¹⁹ = 21120596723 is a prime.

It is a super-2 number, since 2×21121121011² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21121120982 and 21121121000.

It is not an unprimeable number, because it can be changed into a prime (21121151011) 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, 621209425 + ... + 621209458.

It is an arithmetic number, because the mean of its divisors is an integer number (5590884978).

Almost surely, 2^21121121011 is an apocalyptic number.

21121121011 is a deficient number, since it is larger than the sum of its proper divisors (1242418901).

21121121011 is a wasteful number, since it uses less digits than its factorization.

21121121011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1242418900.

The product of its (nonzero) digits is 8, while the sum is 13.

Adding to 21121121011 its reverse (11012112112), we get a palindrome (32133233123).

The spelling of 21121121011 in words is "twenty-one billion, one hundred twenty-one million, one hundred twenty-one thousand, eleven".