21121122110021 has 8 divisors (see below), whose sum is σ = 21125033987064. Its totient is φ = 21117210528960.

The previous prime is 21121122109961. The next prime is 21121122110027. The reversal of 21121122110021 is 12001122112112.

It can be written as a sum of positive squares in 4 ways, for example, as 346797321025 + 20774324788996 = 588895^2 + 4557886^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21121122110021 is a prime.

It is a super-2 number, since 2×21121122110021² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121122110027) 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, 182365151 + ... + 182480931.

It is an arithmetic number, because the mean of its divisors is an integer number (2640629248383).

Almost surely, 2^{21121122110021} is an apocalyptic number.

It is an amenable number.

21121122110021 is a deficient number, since it is larger than the sum of its proper divisors (3911877043).

21121122110021 is a wasteful number, since it uses less digits than its factorization.

21121122110021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 147991.

The product of its (nonzero) digits is 32, while the sum is 17.

Adding to 21121122110021 its reverse (12001122112112), we get a palindrome (33122244222133).

The spelling of 21121122110021 in words is "twenty-one trillion, one hundred twenty-one billion, one hundred twenty-two million, one hundred ten thousand, twenty-one".