13621840 has 40 divisors (see below), whose sum is σ = 32451048. Its totient is φ = 5314560.

The previous prime is 13621831. The next prime is 13621871. The reversal of 13621840 is 4812631.

It can be written as a sum of positive squares in 4 ways, for example, as 1175056 + 12446784 = 1084^2 + 3528^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a hoax number, since the sum of its digits (25) coincides with the sum of the digits of its distinct prime factors.

It is a nialpdrome in base 11.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 1204 + ... + 5356.

Almost surely, 2^13621840 is an apocalyptic number.

13621840 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 13621840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (16225524).

13621840 is an abundant number, since it is smaller than the sum of its proper divisors (18829208).

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

13621840 is a wasteful number, since it uses less digits than its factorization.

13621840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4207 (or 4201 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 25.

The square root of 13621840 is about 3690.7776958251. Note that the first 3 decimals coincide. The cubic root of 13621840 is about 238.8243429568.

The spelling of 13621840 in words is "thirteen million, six hundred twenty-one thousand, eight hundred forty".