665647165440 has 1040 divisors, whose sum is σ = 2489321960928. Its totient is φ = 170039181312.

The previous prime is 665647165411. The next prime is 665647165451. The reversal of 665647165440 is 44561746566.

665647165440 is a `hidden beast` number, since 6 + 6 + 56 + 47 + 1 + 6 + 544 + 0 = 666.

It is a super-2 number, since 2×665647165440² (a number of 24 digits) contains 22 as substring.

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

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 5890682824 + ... + 5890682936.

Almost surely, 2^665647165440 is an apocalyptic number.

665647165440 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 665647165440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1244660980464).

665647165440 is an abundant number, since it is smaller than the sum of its proper divisors (1823674795488).

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

665647165440 is a wasteful number, since it uses less digits than its factorization.

665647165440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 274 (or 243 counting only the distinct ones).

The product of its (nonzero) digits is 14515200, while the sum is 54.

The spelling of 665647165440 in words is "six hundred sixty-five billion, six hundred forty-seven million, one hundred sixty-five thousand, four hundred forty".