21201010021 has 8 divisors (see below), whose sum is σ = 21603440664. Its totient is φ = 20798668800.

The previous prime is 21201010007. The next prime is 21201010057. The reversal of 21201010021 is 12001010212.

It can be written as a sum of positive squares in 4 ways, for example, as 2077992225 + 19123017796 = 45585^2 + 138286^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21201010021 - 2³³ = 12611075429 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201070021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 641125 + ... + 673381.

It is an arithmetic number, because the mean of its divisors is an integer number (2700430083).

Almost surely, 2^21201010021 is an apocalyptic number.

It is an amenable number.

21201010021 is a deficient number, since it is larger than the sum of its proper divisors (402430643).

21201010021 is a wasteful number, since it uses less digits than its factorization.

21201010021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44711.

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 21201010021 its reverse (12001010212), we get a palindrome (33202020233).

The spelling of 21201010021 in words is "twenty-one billion, two hundred one million, ten thousand, twenty-one".