13581064921 has 4 divisors (see below), whose sum is σ = 13597607844. Its totient is φ = 13564522000.

The previous prime is 13581064879. The next prime is 13581064927. The reversal of 13581064921 is 12946018531.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1128960000 + 12452104921 = 33600^2 + 111589^2 .

It is a cyclic number.

It is not a de Polignac number, because 13581064921 - 2⁷ = 13581064793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (13581064927) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8270230 + ... + 8271871.

It is an arithmetic number, because the mean of its divisors is an integer number (3399401961).

Almost surely, 2^13581064921 is an apocalyptic number.

It is an amenable number.

13581064921 is a deficient number, since it is larger than the sum of its proper divisors (16542923).

13581064921 is an equidigital number, since it uses as much as digits as its factorization.

13581064921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16542922.

The product of its (nonzero) digits is 51840, while the sum is 40.

The spelling of 13581064921 in words is "thirteen billion, five hundred eighty-one million, sixty-four thousand, nine hundred twenty-one".