664171920 has 320 divisors, whose sum is σ = 2474841600. Its totient is φ = 163215360.

The previous prime is 664171919. The next prime is 664171927. The reversal of 664171920 is 29171466.

664171920 is a `hidden beast` number, since 6 + 641 + 7 + 1 + 9 + 2 + 0 = 666.

664171920 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×664171920² = 882248678632972800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (664171927) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1440490 + ... + 1440950.

It is an arithmetic number, because the mean of its divisors is an integer number (7733880).

Almost surely, 2^664171920 is an apocalyptic number.

664171920 is a gapful number since it is divisible by the number (60) 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 664171920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1237420800).

664171920 is an abundant number, since it is smaller than the sum of its proper divisors (1810669680).

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

664171920 is a wasteful number, since it uses less digits than its factorization.

664171920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 535 (or 523 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 36.

The square root of 664171920 is about 25771.5331325088. The cubic root of 664171920 is about 872.4894216882.

The spelling of 664171920 in words is "six hundred sixty-four million, one hundred seventy-one thousand, nine hundred twenty".