13220640 has 72 divisors (see below), whose sum is σ = 45120348. Its totient is φ = 3525120.

The previous prime is 13220639. The next prime is 13220659. The reversal of 13220640 is 4602231.

It is a happy number.

13220640 is a `hidden beast` number, since 1 + 3 + 2 + 20 + 640 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 13220496 + 144 = 3636^2 + 12^2 .

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3151 + ... + 6030.

Almost surely, 2^13220640 is an apocalyptic number.

13220640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

13220640 is an abundant number, since it is smaller than the sum of its proper divisors (31899708).

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

13220640 is a wasteful number, since it uses less digits than its factorization.

13220640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9202 (or 9191 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 13220640 is about 3636.0198019263. The cubic root of 13220640 is about 236.4562656489.

Adding to 13220640 its reverse (4602231), we get a palindrome (17822871).

The spelling of 13220640 in words is "thirteen million, two hundred twenty thousand, six hundred forty".