13553821 has 16 divisors (see below), whose sum is σ = 14837760. Its totient is φ = 12337920.

The previous prime is 13553819. The next prime is 13553833. The reversal of 13553821 is 12835531.

13553821 is a nontrivial binomial coefficient, being equal to C(5207, 2).

It is a cyclic number.

It is not a de Polignac number, because 13553821 - 2¹ = 13553819 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 13553821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13553801) 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 15 ways as a sum of consecutive naturals, for example, 98865 + ... + 99001.

It is an arithmetic number, because the mean of its divisors is an integer number (927360).

Almost surely, 2^13553821 is an apocalyptic number.

13553821 is the 5206-th triangular number.

13553821 is the 1736-th centered nonagonal number.

It is an amenable number.

13553821 is a deficient number, since it is larger than the sum of its proper divisors (1283939).

13553821 is a wasteful number, since it uses less digits than its factorization.

13553821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 324.

The product of its digits is 3600, while the sum is 28.

The square root of 13553821 is about 3681.5514392712. The cubic root of 13553821 is about 238.4261660412.

It can be divided in two parts, 135 and 53821, that added together give a triangular number (53956 = T₃₂₈).

The spelling of 13553821 in words is "thirteen million, five hundred fifty-three thousand, eight hundred twenty-one".