18279440 has 40 divisors (see below), whose sum is σ = 43544088. Its totient is φ = 7132160.

The previous prime is 18279431. The next prime is 18279449. The reversal of 18279440 is 4497281.

It is an interprime number because it is at equal distance from previous prime (18279431) and next prime (18279449).

It can be written as a sum of positive squares in 4 ways, for example, as 1106704 + 17172736 = 1052^2 + 4144^2 .

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

It is a self number, because there is not a number n which added to its sum of digits gives 18279440.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18279449) 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, 494 + ... + 6066.

Almost surely, 2^18279440 is an apocalyptic number.

18279440 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 18279440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21772044).

18279440 is an abundant number, since it is smaller than the sum of its proper divisors (25264648).

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

18279440 is a wasteful number, since it uses less digits than its factorization.

18279440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5627 (or 5621 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 35.

The square root of 18279440 is about 4275.4461755471. The cubic root of 18279440 is about 263.4233664619.

The spelling of 18279440 in words is "eighteen million, two hundred seventy-nine thousand, four hundred forty".