19643940 has 36 divisors (see below), whose sum is σ = 59587164. Its totient is φ = 5238336.

The previous prime is 19643839. The next prime is 19643941. The reversal of 19643940 is 4934691.

19643940 is a `hidden beast` number, since 1 + 9 + 643 + 9 + 4 + 0 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 8714304 + 10929636 = 2952^2 + 3306^2 .

It is a tau number, because it is divible by the number of its divisors (36).

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 = 19643895 and 19643904.

It is not an unprimeable number, because it can be changed into a prime (19643941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 54387 + ... + 54746.

It is an arithmetic number, because the mean of its divisors is an integer number (1655199).

Almost surely, 2^19643940 is an apocalyptic number.

19643940 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

19643940 is an abundant number, since it is smaller than the sum of its proper divisors (39943224).

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

19643940 is a wasteful number, since it uses less digits than its factorization.

19643940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 109148 (or 109143 counting only the distinct ones).

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

The square root of 19643940 is about 4432.1484632174. The cubic root of 19643940 is about 269.8212809049.

The spelling of 19643940 in words is "nineteen million, six hundred forty-three thousand, nine hundred forty".