21131221011 has 8 divisors (see below), whose sum is σ = 28361551104. Its totient is φ = 13994185800.

The previous prime is 21131220989. The next prime is 21131221063. The reversal of 21131221011 is 11012213112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21131221011 - 2⁷ = 21131220883 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21131222011) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23323191 + ... + 23324096.

It is an arithmetic number, because the mean of its divisors is an integer number (3545193888).

Almost surely, 2^21131221011 is an apocalyptic number.

21131221011 is a deficient number, since it is larger than the sum of its proper divisors (7230330093).

21131221011 is a wasteful number, since it uses less digits than its factorization.

21131221011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46647441.

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

Adding to 21131221011 its reverse (11012213112), we get a palindrome (32143434123).

The spelling of 21131221011 in words is "twenty-one billion, one hundred thirty-one million, two hundred twenty-one thousand, eleven".