16521099989 has 2 divisors, whose sum is σ = 16521099990. Its totient is φ = 16521099988.

The previous prime is 16521099983. The next prime is 16521100009. The reversal of 16521099989 is 98999012561.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10770911089 + 5750188900 = 103783^2 + 75830^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16521099989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16521099983) 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 as a sum of consecutive naturals, namely, 8260549994 + 8260549995.

It is an arithmetic number, because the mean of its divisors is an integer number (8260549995).

Almost surely, 2^16521099989 is an apocalyptic number.

It is an amenable number.

16521099989 is a deficient number, since it is larger than the sum of its proper divisors (1).

16521099989 is an equidigital number, since it uses as much as digits as its factorization.

16521099989 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3149280, while the sum is 59.

The spelling of 16521099989 in words is "sixteen billion, five hundred twenty-one million, ninety-nine thousand, nine hundred eighty-nine".