19901664 has 72 divisors (see below), whose sum is σ = 59590440. Its totient is φ = 6283008.

The previous prime is 19901663. The next prime is 19901681. The reversal of 19901664 is 46610991.

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 congruent number.

It is not an unprimeable number, because it can be changed into a prime (19901663) 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, 3654 + ... + 7290.

It is an arithmetic number, because the mean of its divisors is an integer number (827645).

Almost surely, 2^19901664 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19901664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29795220).

19901664 is an abundant number, since it is smaller than the sum of its proper divisors (39688776).

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

19901664 is a wasteful number, since it uses less digits than its factorization.

19901664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3672 (or 3661 counting only the distinct ones).

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

The square root of 19901664 is about 4461.1281084497. The cubic root of 19901664 is about 270.9961555897.

The spelling of 19901664 in words is "nineteen million, nine hundred one thousand, six hundred sixty-four".