13821720 has 128 divisors (see below), whose sum is σ = 46621440. Its totient is φ = 3248640.

The previous prime is 13821707. The next prime is 13821733. The reversal of 13821720 is 2712831.

13821720 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (13821707) and next prime (13821733).

It is a super-3 number, since 3×13821720³ (a number of 22 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 48699 + ... + 48981.

It is an arithmetic number, because the mean of its divisors is an integer number (364230).

Almost surely, 2^13821720 is an apocalyptic number.

13821720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 13821720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23310720).

13821720 is an abundant number, since it is smaller than the sum of its proper divisors (32799720).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

13821720 is a wasteful number, since it uses less digits than its factorization.

13821720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 345 (or 341 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 24.

The square root of 13821720 is about 3717.7573885341. The cubic root of 13821720 is about 239.9868048301.

Subtracting from 13821720 its reverse (2712831), we obtain a square (11108889 = 3333²).

It can be divided in two parts, 13821 and 720, that added together give a palindrome (14541).

The spelling of 13821720 in words is "thirteen million, eight hundred twenty-one thousand, seven hundred twenty".