21636350649 has 9 divisors (see below), whose sum is σ = 31253143909. Its totient is φ = 14423939580.

The previous prime is 21636350641. The next prime is 21636350651. The reversal of 21636350649 is 94605363612.

The square root of 21636350649 is 147093.

It is a perfect power (a square), and thus also a powerful number.

21636350649 is a `hidden beast` number, since 2 + 1 + 6 + 3 + 635 + 0 + 6 + 4 + 9 = 666.

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 21636350649 - 2³ = 21636350641 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21636350641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 416764 + ... + 465794.

Almost surely, 2^21636350649 is an apocalyptic number.

21636350649 is the 147093-rd square number.

21636350649 is the 73547-th centered octagonal number.

It is an amenable number.

21636350649 is a deficient number, since it is larger than the sum of its proper divisors (9616793260).

21636350649 is an frugal number, since it uses more digits than its factorization.

21636350649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 98068 (or 49034 counting only the distinct ones).

The product of its (nonzero) digits is 699840, while the sum is 45.

The spelling of 21636350649 in words is "twenty-one billion, six hundred thirty-six million, three hundred fifty thousand, six hundred forty-nine".