21021110989 has 2 divisors, whose sum is σ = 21021110990. Its totient is φ = 21021110988.

The previous prime is 21021110977. The next prime is 21021111029. The reversal of 21021110989 is 98901112012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20403836964 + 617274025 = 142842^2 + 24845^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21021110989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21021110969) 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 as a sum of consecutive naturals, namely, 10510555494 + 10510555495.

It is an arithmetic number, because the mean of its divisors is an integer number (10510555495).

Almost surely, 2^21021110989 is an apocalyptic number.

It is an amenable number.

21021110989 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021110989 is an equidigital number, since it uses as much as digits as its factorization.

21021110989 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2592, while the sum is 34.

The spelling of 21021110989 in words is "twenty-one billion, twenty-one million, one hundred ten thousand, nine hundred eighty-nine".