21609028773 has 10 divisors (see below), whose sum is σ = 32280154214. Its totient is φ = 14406019128.

The previous prime is 21609028741. The next prime is 21609028807. The reversal of 21609028773 is 37782090612.

21609028773 is a `hidden beast` number, since 216 + 0 + 90 + 287 + 73 = 666.

It can be written as a sum of positive squares in only one way, i.e., 11198295684 + 10410733089 = 105822^2 + 102033^2 .

It is not a de Polignac number, because 21609028773 - 2⁵ = 21609028741 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21609028703) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 133388986 + ... + 133389147.

Almost surely, 2^21609028773 is an apocalyptic number.

It is an amenable number.

21609028773 is a deficient number, since it is larger than the sum of its proper divisors (10671125441).

21609028773 is an equidigital number, since it uses as much as digits as its factorization.

21609028773 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 266778145 (or 266778136 counting only the distinct ones).

The product of its (nonzero) digits is 254016, while the sum is 45.

The spelling of 21609028773 in words is "twenty-one billion, six hundred nine million, twenty-eight thousand, seven hundred seventy-three".