665872721280 has 1536 divisors, whose sum is σ = 2731091126400. Its totient is φ = 153837895680.

The previous prime is 665872721249. The next prime is 665872721287. The reversal of 665872721280 is 82127278566.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665872721287) by changing a digit.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 2403872502 + ... + 2403872778.

Almost surely, 2^665872721280 is an apocalyptic number.

665872721280 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 665872721280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1365545563200).

665872721280 is an abundant number, since it is smaller than the sum of its proper divisors (2065218405120).

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

665872721280 is a wasteful number, since it uses less digits than its factorization.

665872721280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 394 (or 370 counting only the distinct ones).

The product of its (nonzero) digits is 4515840, while the sum is 54.

The spelling of 665872721280 in words is "six hundred sixty-five billion, eight hundred seventy-two million, seven hundred twenty-one thousand, two hundred eighty".