17978240 has 64 divisors (see below), whose sum is σ = 49131360. Its totient is φ = 6162432.

The previous prime is 17978239. The next prime is 17978243. The reversal of 17978240 is 4287971.

It is a tau number, because it is divible by the number of its divisors (64).

It is a super-2 number, since 2×17978240² = 646434226995200, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 17978194 and 17978203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (17978243) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2474 + ... + 6486.

Almost surely, 2^17978240 is an apocalyptic number.

17978240 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 17978240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24565680).

17978240 is an abundant number, since it is smaller than the sum of its proper divisors (31153120).

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

17978240 is an equidigital number, since it uses as much as digits as its factorization.

17978240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4039 (or 4027 counting only the distinct ones).

The product of its (nonzero) digits is 28224, while the sum is 38.

The square root of 17978240 is about 4240.0754710264. The cubic root of 17978240 is about 261.9684906652.

The spelling of 17978240 in words is "seventeen million, nine hundred seventy-eight thousand, two hundred forty".