13563661221 has 32 divisors (see below), whose sum is σ = 22066314240. Its totient is φ = 8165934000.

The previous prime is 13563661159. The next prime is 13563661247. The reversal of 13563661221 is 12216636531.

13563661221 is a `hidden beast` number, since 1 + 3 + 5 + 6 + 36 + 612 + 2 + 1 = 666.

It is a de Polignac number, because none of the positive numbers 2^k-13563661221 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13563661721) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 106375 + ... + 196068.

It is an arithmetic number, because the mean of its divisors is an integer number (689572320).

Almost surely, 2^13563661221 is an apocalyptic number.

13563661221 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

13563661221 is a deficient number, since it is larger than the sum of its proper divisors (8502653019).

13563661221 is a wasteful number, since it uses less digits than its factorization.

13563661221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 302614 (or 302608 counting only the distinct ones).

The product of its digits is 38880, while the sum is 36.

The spelling of 13563661221 in words is "thirteen billion, five hundred sixty-three million, six hundred sixty-one thousand, two hundred twenty-one".