13656821 has 2 divisors, whose sum is σ = 13656822. Its totient is φ = 13656820.

The previous prime is 13656791. The next prime is 13656827. The reversal of 13656821 is 12865631.

It is a happy number.

13656821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13586596 + 70225 = 3686^2 + 265^2 .

It is an emirp because it is prime and its reverse (12865631) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 13656821 - 2¹⁰ = 13655797 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (13656827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6828410 + 6828411.

It is an arithmetic number, because the mean of its divisors is an integer number (6828411).

Almost surely, 2^13656821 is an apocalyptic number.

It is an amenable number.

13656821 is a deficient number, since it is larger than the sum of its proper divisors (1).

13656821 is an equidigital number, since it uses as much as digits as its factorization.

13656821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8640, while the sum is 32.

The square root of 13656821 is about 3695.5136314185. The cubic root of 13656821 is about 239.0286025186.

The spelling of 13656821 in words is "thirteen million, six hundred fifty-six thousand, eight hundred twenty-one".