19943640 has 48 divisors (see below), whose sum is σ = 64818000. Its totient is φ = 5318208.

The previous prime is 19943639. The next prime is 19943659. The reversal of 19943640 is 4634991.

19943640 is a `hidden beast` number, since 1 + 9 + 9 + 4 + 3 + 640 = 666.

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 = 19943595 and 19943604.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 27340 + ... + 28059.

It is an arithmetic number, because the mean of its divisors is an integer number (1350375).

Almost surely, 2^19943640 is an apocalyptic number.

19943640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

19943640 is an abundant number, since it is smaller than the sum of its proper divisors (44874360).

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

19943640 is a wasteful number, since it uses less digits than its factorization.

19943640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55416 (or 55409 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 36.

The square root of 19943640 is about 4465.8302699498. The cubic root of 19943640 is about 271.1865474832.

The spelling of 19943640 in words is "nineteen million, nine hundred forty-three thousand, six hundred forty".