16561621093 has 2 divisors, whose sum is σ = 16561621094. Its totient is φ = 16561621092.

The previous prime is 16561621081. The next prime is 16561621123. The reversal of 16561621093 is 39012616561.

It is a happy number.

16561621093 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13022917924 + 3538703169 = 114118^2 + 59487^2 .

It is an emirp because it is prime and its reverse (39012616561) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16561621093 - 2¹³ = 16561612901 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16561621003) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8280810546 + 8280810547.

It is an arithmetic number, because the mean of its divisors is an integer number (8280810547).

Almost surely, 2^16561621093 is an apocalyptic number.

It is an amenable number.

16561621093 is a deficient number, since it is larger than the sum of its proper divisors (1).

16561621093 is an equidigital number, since it uses as much as digits as its factorization.

16561621093 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 58320, while the sum is 40.

The spelling of 16561621093 in words is "sixteen billion, five hundred sixty-one million, six hundred twenty-one thousand, ninety-three".