21121231011 has 4 divisors (see below), whose sum is σ = 28161641352. Its totient is φ = 14080820672.

The previous prime is 21121231009. The next prime is 21121231063. The reversal of 21121231011 is 11013212112.

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 21121231011 - 2¹ = 21121231009 is a prime.

It is a super-2 number, since 2×21121231011² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21121231091) 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, 3520205166 + ... + 3520205171.

It is an arithmetic number, because the mean of its divisors is an integer number (7040410338).

Almost surely, 2^21121231011 is an apocalyptic number.

21121231011 is a deficient number, since it is larger than the sum of its proper divisors (7040410341).

21121231011 is an equidigital number, since it uses as much as digits as its factorization.

21121231011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7040410340.

The product of its (nonzero) digits is 24, while the sum is 15.

Adding to 21121231011 its reverse (11013212112), we get a palindrome (32134443123).

The spelling of 21121231011 in words is "twenty-one billion, one hundred twenty-one million, two hundred thirty-one thousand, eleven".