21101111220021 has 16 divisors (see below), whose sum is σ = 32258810648064. Its totient is φ = 12018501687024.

The previous prime is 21101111220019. The next prime is 21101111220047. The reversal of 21101111220021 is 12002211110112.

It is a happy number.

It is not a de Polignac number, because 21101111220021 - 2¹ = 21101111220019 is a prime.

It is a super-2 number, since 2×21101111220021² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21101111220221) 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, 1636499775 + ... + 1636512668.

It is an arithmetic number, because the mean of its divisors is an integer number (2016175665504).

Almost surely, 2^{21101111220021} is an apocalyptic number.

21101111220021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21101111220021 is a deficient number, since it is larger than the sum of its proper divisors (11157699428043).

21101111220021 is a wasteful number, since it uses less digits than its factorization.

21101111220021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3273012760.

The product of its (nonzero) digits is 16, while the sum is 15.

Adding to 21101111220021 its reverse (12002211110112), we get a palindrome (33103322330133).

The spelling of 21101111220021 in words is "twenty-one trillion, one hundred one billion, one hundred eleven million, two hundred twenty thousand, twenty-one".