19945440 has 216 divisors, whose sum is σ = 74397960. Its totient is φ = 5038848.

The previous prime is 19945427. The next prime is 19945447. The reversal of 19945440 is 4454991.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (216).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 19945395 and 19945404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19945447) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 1049751 + ... + 1049769.

It is an arithmetic number, because the mean of its divisors is an integer number (344435).

Almost surely, 2^19945440 is an apocalyptic number.

19945440 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 19945440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37198980).

19945440 is an abundant number, since it is smaller than the sum of its proper divisors (54452520).

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

19945440 is an frugal number, since it uses more digits than its factorization.

19945440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58 (or 29 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 36.

The square root of 19945440 is about 4466.0317956772. The cubic root of 19945440 is about 271.1947058251.

The spelling of 19945440 in words is "nineteen million, nine hundred forty-five thousand, four hundred forty".