21111021230021 has 2 divisors, whose sum is σ = 21111021230022. Its totient is φ = 21111021230020.

The previous prime is 21111021229997. The next prime is 21111021230069. The reversal of 21111021230021 is 12003212011112.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12791430933121 + 8319590296900 = 3576511^2 + 2884370^2 .

It is a cyclic number.

It is not a de Polignac number, because 21111021230021 - 2¹⁴ = 21111021213637 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21111021230081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10555510615010 + 10555510615011.

It is an arithmetic number, because the mean of its divisors is an integer number (10555510615011).

Almost surely, 2^{21111021230021} is an apocalyptic number.

It is an amenable number.

21111021230021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21111021230021 is an equidigital number, since it uses as much as digits as its factorization.

21111021230021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 48, while the sum is 17.

Adding to 21111021230021 its reverse (12003212011112), we get a palindrome (33114233241133).

The spelling of 21111021230021 in words is "twenty-one trillion, one hundred eleven billion, twenty-one million, two hundred thirty thousand, twenty-one".