20171664 has 60 divisors (see below), whose sum is σ = 56948736. Its totient is φ = 6664896.

The previous prime is 20171653. The next prime is 20171681. The reversal of 20171664 is 46617102.

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, 17737 + ... + 18839.

Almost surely, 2^20171664 is an apocalyptic number.

20171664 is a gapful number since it is divisible by the number (24) 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 20171664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28474368).

20171664 is an abundant number, since it is smaller than the sum of its proper divisors (36777072).

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

20171664 is a wasteful number, since it uses less digits than its factorization.

20171664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1244 (or 1235 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 20171664 is about 4491.2875659436. The cubic root of 20171664 is about 272.2161632292.

Adding to 20171664 its reverse (46617102), we get a palindrome (66788766).

The spelling of 20171664 in words is "twenty million, one hundred seventy-one thousand, six hundred sixty-four".