21201210021 has 8 divisors (see below), whose sum is σ = 29756084320. Its totient is φ = 13390237872.

The previous prime is 21201210007. The next prime is 21201210047. The reversal of 21201210021 is 12001210212.

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

It is not a de Polignac number, because 21201210021 - 2⁶ = 21201209957 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21201209979 and 21201210006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201210091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 185975470 + ... + 185975583.

It is an arithmetic number, because the mean of its divisors is an integer number (3719510540).

Almost surely, 2^21201210021 is an apocalyptic number.

It is an amenable number.

21201210021 is a deficient number, since it is larger than the sum of its proper divisors (8554874299).

21201210021 is a wasteful number, since it uses less digits than its factorization.

21201210021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 371951075.

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21201210021 its reverse (12001210212), we get a palindrome (33202420233).

The spelling of 21201210021 in words is "twenty-one billion, two hundred one million, two hundred ten thousand, twenty-one".