19997440 has 72 divisors (see below), whose sum is σ = 50772960. Its totient is φ = 7520256.

The previous prime is 19997413. The next prime is 19997441. The reversal of 19997440 is 4479991.

It is not an unprimeable number, because it can be changed into a prime (19997441) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 21301 + ... + 22219.

It is an arithmetic number, because the mean of its divisors is an integer number (705180).

Almost surely, 2^19997440 is an apocalyptic number.

19997440 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 19997440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25386480).

19997440 is an abundant number, since it is smaller than the sum of its proper divisors (30775520).

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

19997440 is an equidigital number, since it uses as much as digits as its factorization.

19997440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 957 (or 943 counting only the distinct ones).

The product of its (nonzero) digits is 81648, while the sum is 43.

The square root of 19997440 is about 4471.8497291389. The cubic root of 19997440 is about 271.4301796501.

The spelling of 19997440 in words is "nineteen million, nine hundred ninety-seven thousand, four hundred forty".