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18997440 = 2635711257

18997440 has 224 divisors, whose sum is σ = 75492864. Its totient is φ = 3932160.

The previous prime is 18997439. The next prime is 18997441. The reversal of 18997440 is 4479981.

It is an interprime number because it is at equal distance from previous prime (18997439) and next prime (18997441).

It is a tau number, because it is divible by the number of its divisors (224).

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a junction number, because it is equal to n+sod(n) for n = 18997392 and 18997401.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18997441) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 73792 + ... + 74048.

Almost surely, 218997440 is an apocalyptic number.

18997440 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 18997440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37746432).

18997440 is an abundant number, since it is smaller than the sum of its proper divisors (56495424).

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

18997440 is a wasteful number, since it uses less digits than its factorization.

18997440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 295 (or 285 counting only the distinct ones).

The product of its (nonzero) digits is 72576, while the sum is 42.

The square root of 18997440 is about 4358.6052815092. The cubic root of 18997440 is about 266.8281799335.

It can be divided in two parts, 1899 and 7440, that added together give a palindrome (9339).

The spelling of 18997440 in words is "eighteen million, nine hundred ninety-seven thousand, four hundred forty".