19664000 has 64 divisors (see below), whose sum is σ = 48929400. Its totient is φ = 7859200.

The previous prime is 19663999. The next prime is 19664003. The reversal of 19664000 is 46691.

It can be written as a sum of positive squares in 4 ways, for example, as 12222016 + 7441984 = 3496^2 + 2728^2 .

It is a tau number, because it is divible by the number of its divisors (64).

It is not an unprimeable number, because it can be changed into a prime (19664003) 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, 15386 + ... + 16614.

Almost surely, 2^19664000 is an apocalyptic number.

19664000 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 19664000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24464700).

19664000 is an abundant number, since it is smaller than the sum of its proper divisors (29265400).

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

19664000 is an equidigital number, since it uses as much as digits as its factorization.

19664000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1258 (or 1236 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 26.

The square root of 19664000 is about 4434.4108966130. The cubic root of 19664000 is about 269.9130950304.

The spelling of 19664000 in words is "nineteen million, six hundred sixty-four thousand".