13645611561 has 24 divisors (see below), whose sum is σ = 19339231680. Its totient is φ = 8556689152.

The previous prime is 13645611547. The next prime is 13645611569. The reversal of 13645611561 is 16511654631.

It is not a de Polignac number, because 13645611561 - 2¹⁷ = 13645480489 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (13645611569) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1790020 + ... + 1797626.

It is an arithmetic number, because the mean of its divisors is an integer number (805801320).

Almost surely, 2^13645611561 is an apocalyptic number.

It is an amenable number.

13645611561 is a deficient number, since it is larger than the sum of its proper divisors (5693620119).

13645611561 is a wasteful number, since it uses less digits than its factorization.

13645611561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9713 (or 9696 counting only the distinct ones).

The product of its digits is 64800, while the sum is 39.

It can be divided in two parts, 1364 and 5611561, that added together give a triangular number (5612925 = T₃₃₅₀).

The spelling of 13645611561 in words is "thirteen billion, six hundred forty-five million, six hundred eleven thousand, five hundred sixty-one".