21123303021 has 6 divisors (see below), whose sum is σ = 30511437710. Its totient is φ = 14082202008.

The previous prime is 21123302969. The next prime is 21123303037. The reversal of 21123303021 is 12030332112.

21123303021 is a `hidden beast` number, since 21 + 12 + 330 + 302 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 11446646121 + 9676656900 = 106989^2 + 98370^2 .

It is not a de Polignac number, because 21123303021 - 2⁶ = 21123302957 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 = 21123302985 and 21123303003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21123303221) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1173516826 + ... + 1173516843.

Almost surely, 2^21123303021 is an apocalyptic number.

It is an amenable number.

21123303021 is a deficient number, since it is larger than the sum of its proper divisors (9388134689).

21123303021 is a wasteful number, since it uses less digits than its factorization.

21123303021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2347033675 (or 2347033672 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 18.

Adding to 21123303021 its reverse (12030332112), we get a palindrome (33153635133).

The spelling of 21123303021 in words is "twenty-one billion, one hundred twenty-three million, three hundred three thousand, twenty-one".