21008989811 has 2 divisors, whose sum is σ = 21008989812. Its totient is φ = 21008989810.

The previous prime is 21008989789. The next prime is 21008989907. The reversal of 21008989811 is 11898980012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21008989811 - 2⁶ = 21008989747 is a prime.

It is not a weakly prime, because it can be changed into another prime (21008989511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10504494905 + 10504494906.

It is an arithmetic number, because the mean of its divisors is an integer number (10504494906).

Almost surely, 2^21008989811 is an apocalyptic number.

21008989811 is a deficient number, since it is larger than the sum of its proper divisors (1).

21008989811 is an equidigital number, since it uses as much as digits as its factorization.

21008989811 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 82944, while the sum is 47.

The spelling of 21008989811 in words is "twenty-one billion, eight million, nine hundred eighty-nine thousand, eight hundred eleven".