21012000221 has 16 divisors (see below), whose sum is σ = 23221728000. Its totient is φ = 18910940928.

The previous prime is 21012000209. The next prime is 21012000227. The reversal of 21012000221 is 12200021012.

It is a happy number.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21012000221 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012000227) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2419475 + ... + 2428143.

It is an arithmetic number, because the mean of its divisors is an integer number (1451358000).

Almost surely, 2^21012000221 is an apocalyptic number.

It is an amenable number.

21012000221 is a deficient number, since it is larger than the sum of its proper divisors (2209727779).

21012000221 is a wasteful number, since it uses less digits than its factorization.

21012000221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14908.

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 21012000221 its reverse (12200021012), we get a palindrome (33212021233).

The spelling of 21012000221 in words is "twenty-one billion, twelve million, two hundred twenty-one", and thus it is an aban number.