665642641320 has 64 divisors (see below), whose sum is σ = 2218808808000. Its totient is φ = 177504704064.

The previous prime is 665642641291. The next prime is 665642641333. The reversal of 665642641320 is 23146246566.

It is a happy number.

665642641320 is a `hidden beast` number, since 6 + 6 + 5 + 64 + 264 + 1 + 320 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 308166810 + ... + 308168969.

It is an arithmetic number, because the mean of its divisors is an integer number (34668887625).

Almost surely, 2^665642641320 is an apocalyptic number.

665642641320 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

665642641320 is an abundant number, since it is smaller than the sum of its proper divisors (1553166166680).

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

665642641320 is a wasteful number, since it uses less digits than its factorization.

665642641320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 616335799 (or 616335789 counting only the distinct ones).

The product of its (nonzero) digits is 1244160, while the sum is 45.

Adding to 665642641320 its reverse (23146246566), we get a palindrome (688788887886).

The spelling of 665642641320 in words is "six hundred sixty-five billion, six hundred forty-two million, six hundred forty-one thousand, three hundred twenty".