21110213021 has 4 divisors (see below), whose sum is σ = 21118751772. Its totient is φ = 21101674272.

The previous prime is 21110213009. The next prime is 21110213057. The reversal of 21110213021 is 12031201112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 11645647225 + 9464565796 = 107915^2 + 97286^2 .

It is a cyclic number.

It is not a de Polignac number, because 21110213021 - 2³⁰ = 20036471197 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21110212987 and 21110213005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21110213221) 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, 4265666 + ... + 4270611.

It is an arithmetic number, because the mean of its divisors is an integer number (5279687943).

Almost surely, 2^21110213021 is an apocalyptic number.

It is an amenable number.

21110213021 is a deficient number, since it is larger than the sum of its proper divisors (8538751).

21110213021 is an equidigital number, since it uses as much as digits as its factorization.

21110213021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8538750.

The product of its (nonzero) digits is 24, while the sum is 14.

Adding to 21110213021 its reverse (12031201112), we get a palindrome (33141414133).

The spelling of 21110213021 in words is "twenty-one billion, one hundred ten million, two hundred thirteen thousand, twenty-one".