13640240 has 20 divisors (see below), whose sum is σ = 31713744. Its totient is φ = 5456064.

The previous prime is 13640213. The next prime is 13640257. The reversal of 13640240 is 4204631.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (20).

It is a super-2 number, since 2×13640240² = 372112294515200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 85172 + ... + 85331.

Almost surely, 2^13640240 is an apocalyptic number.

13640240 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

13640240 is an abundant number, since it is smaller than the sum of its proper divisors (18073504).

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

13640240 is a wasteful number, since it uses less digits than its factorization.

13640240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 170516 (or 170510 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 20.

The square root of 13640240 is about 3693.2695542026. The cubic root of 13640240 is about 238.9318269873.

Adding to 13640240 its reverse (4204631), we get a palindrome (17844871).

The spelling of 13640240 in words is "thirteen million, six hundred forty thousand, two hundred forty".