13856821 has 16 divisors (see below), whose sum is σ = 15588288. Its totient is φ = 12211200.

The previous prime is 13856789. The next prime is 13856831. The reversal of 13856821 is 12865831.

13856821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 13856821 - 2⁵ = 13856789 is a prime.

It is a super-2 number, since 2×13856821² = 384022976452082, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13856831) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 71701 + ... + 71893.

It is an arithmetic number, because the mean of its divisors is an integer number (974268).

Almost surely, 2^13856821 is an apocalyptic number.

13856821 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

13856821 is a deficient number, since it is larger than the sum of its proper divisors (1731467).

13856821 is a wasteful number, since it uses less digits than its factorization.

13856821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 372.

The product of its digits is 11520, while the sum is 34.

The square root of 13856821 is about 3722.4751174454. The cubic root of 13856821 is about 240.1897862247.

The spelling of 13856821 in words is "thirteen million, eight hundred fifty-six thousand, eight hundred twenty-one".