661002718320 has 1280 divisors, whose sum is σ = 2762583183360. Its totient is φ = 142132838400.

The previous prime is 661002718303. The next prime is 661002718373. The reversal of 661002718320 is 23817200166.

661002718320 is a `hidden beast` number, since 6 + 61 + 0 + 0 + 271 + 8 + 320 = 666.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 255 ways as a sum of consecutive naturals, for example, 3651948630 + ... + 3651948810.

It is an arithmetic number, because the mean of its divisors is an integer number (2158268112).

Almost surely, 2^661002718320 is an apocalyptic number.

661002718320 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 661002718320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1381291591680).

661002718320 is an abundant number, since it is smaller than the sum of its proper divisors (2101580465040).

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

661002718320 is a wasteful number, since it uses less digits than its factorization.

661002718320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 431 (or 419 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 36.

Adding to 661002718320 its reverse (23817200166), we get a palindrome (684819918486).

The spelling of 661002718320 in words is "six hundred sixty-one billion, two million, seven hundred eighteen thousand, three hundred twenty".