21111021012221 has 8 divisors (see below), whose sum is σ = 24133848230784. Its totient is φ = 18089935562160.

The previous prime is 21111021012209. The next prime is 21111021012223. The reversal of 21111021012221 is 12221012011112.

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

It is a de Polignac number, because none of the positive numbers 2^k-21111021012221 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21111021012221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21111021012223) 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, 435416150 + ... + 435464631.

It is an arithmetic number, because the mean of its divisors is an integer number (3016731028848).

Almost surely, 2^{21111021012221} is an apocalyptic number.

It is an amenable number.

21111021012221 is a deficient number, since it is larger than the sum of its proper divisors (3022827218563).

21111021012221 is an equidigital number, since it uses as much as digits as its factorization.

21111021012221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 870884251.

The product of its (nonzero) digits is 32, while the sum is 17.

Adding to 21111021012221 its reverse (12221012011112), we get a palindrome (33332033023333).

The spelling of 21111021012221 in words is "twenty-one trillion, one hundred eleven billion, twenty-one million, twelve thousand, two hundred twenty-one".