664961544 has 192 divisors, whose sum is σ = 2063880000. Its totient is φ = 191725056.

The previous prime is 664961537. The next prime is 664961567. The reversal of 664961544 is 445169466.

It is a happy number.

664961544 is a `hidden beast` number, since 6 + 6 + 49 + 61 + 544 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 664961544.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2471842 + ... + 2472110.

It is an arithmetic number, because the mean of its divisors is an integer number (10749375).

Almost surely, 2^664961544 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 664961544, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1031940000).

664961544 is an abundant number, since it is smaller than the sum of its proper divisors (1398918456).

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

664961544 is a wasteful number, since it uses less digits than its factorization.

664961544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 452 (or 445 counting only the distinct ones).

The product of its digits is 622080, while the sum is 45.

The square root of 664961544 is about 25786.8482758169. The cubic root of 664961544 is about 872.8350479353.

The spelling of 664961544 in words is "six hundred sixty-four million, nine hundred sixty-one thousand, five hundred forty-four".