21120012011 has 4 divisors (see below), whose sum is σ = 24137156592. Its totient is φ = 18102867432.

The previous prime is 21120012007. The next prime is 21120012013. The reversal of 21120012011 is 11021002112.

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 21120012011 - 2² = 21120012007 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21120011983 and 21120012001.

It is not an unprimeable number, because it can be changed into a prime (21120012013) 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, 1508572280 + ... + 1508572293.

It is an arithmetic number, because the mean of its divisors is an integer number (6034289148).

Almost surely, 2^21120012011 is an apocalyptic number.

21120012011 is a deficient number, since it is larger than the sum of its proper divisors (3017144581).

21120012011 is an equidigital number, since it uses as much as digits as its factorization.

21120012011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3017144580.

The product of its (nonzero) digits is 8, while the sum is 11.

Adding to 21120012011 its reverse (11021002112), we get a palindrome (32141014123).

The spelling of 21120012011 in words is "twenty-one billion, one hundred twenty million, twelve thousand, eleven".