21003549989 has 2 divisors, whose sum is σ = 21003549990. Its totient is φ = 21003549988.

The previous prime is 21003549949. The next prime is 21003550013. The reversal of 21003549989 is 98994530012.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20894702500 + 108847489 = 144550^2 + 10433^2 .

It is a cyclic number.

It is not a de Polignac number, because 21003549989 - 2²⁰ = 21002501413 is a prime.

It is a super-2 number, since 2×21003549989² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21003549949) 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, 10501774994 + 10501774995.

It is an arithmetic number, because the mean of its divisors is an integer number (10501774995).

Almost surely, 2^21003549989 is an apocalyptic number.

It is an amenable number.

21003549989 is a deficient number, since it is larger than the sum of its proper divisors (1).

21003549989 is an equidigital number, since it uses as much as digits as its factorization.

21003549989 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 699840, while the sum is 50.

The spelling of 21003549989 in words is "twenty-one billion, three million, five hundred forty-nine thousand, nine hundred eighty-nine".