21201045021 has 24 divisors (see below), whose sum is σ = 33349974840. Its totient is φ = 12900197376.

The previous prime is 21201045007. The next prime is 21201045091. The reversal of 21201045021 is 12054010212.

21201045021 is a `hidden beast` number, since 212 + 0 + 1 + 0 + 450 + 2 + 1 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 1192942521 + 20008102500 = 34539^2 + 141450^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21201045021 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21201044985 and 21201045003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201045091) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1007596 + ... + 1028421.

It is an arithmetic number, because the mean of its divisors is an integer number (1389582285).

Almost surely, 2^21201045021 is an apocalyptic number.

It is an amenable number.

21201045021 is a deficient number, since it is larger than the sum of its proper divisors (12148929819).

21201045021 is a wasteful number, since it uses less digits than its factorization.

21201045021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2036125 (or 2036122 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 18.

Adding to 21201045021 its reverse (12054010212), we get a palindrome (33255055233).

The spelling of 21201045021 in words is "twenty-one billion, two hundred one million, forty-five thousand, twenty-one".