19916640 has 72 divisors (see below), whose sum is σ = 67970448. Its totient is φ = 5310720.

The previous prime is 19916629. The next prime is 19916653. The reversal of 19916640 is 4661991.

19916640 is a `hidden beast` number, since 1 + 9 + 9 + 1 + 6 + 640 = 666.

It is a tau number, because it is divible by the number of its divisors (72).

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 = 19916595 and 19916604.

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, 5476 + ... + 8355.

It is an arithmetic number, because the mean of its divisors is an integer number (944034).

Almost surely, 2^19916640 is an apocalyptic number.

19916640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

19916640 is an abundant number, since it is smaller than the sum of its proper divisors (48053808).

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

19916640 is a wasteful number, since it uses less digits than its factorization.

19916640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13852 (or 13841 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 36.

The square root of 19916640 is about 4462.8062920095. The cubic root of 19916640 is about 271.0641134057.

The spelling of 19916640 in words is "nineteen million, nine hundred sixteen thousand, six hundred forty".