21121110021 has 16 divisors (see below), whose sum is σ = 30736093248. Its totient is φ = 12794640000.

The previous prime is 21121109923. The next prime is 21121110037. The reversal of 21121110021 is 12001112112.

It is not a de Polignac number, because 21121110021 - 2¹⁸ = 21120847877 is a prime.

It is a super-2 number, since 2×21121110021² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21121109979 and 21121110006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121110041) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 79230 + ... + 220271.

It is an arithmetic number, because the mean of its divisors is an integer number (1921005828).

Almost surely, 2^21121110021 is an apocalyptic number.

It is an amenable number.

21121110021 is a deficient number, since it is larger than the sum of its proper divisors (9614983227).

21121110021 is a wasteful number, since it uses less digits than its factorization.

21121110021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 301652.

The product of its (nonzero) digits is 8, while the sum is 12.

Adding to 21121110021 its reverse (12001112112), we get a palindrome (33122222133).

The spelling of 21121110021 in words is "twenty-one billion, one hundred twenty-one million, one hundred ten thousand, twenty-one".