665078400 has 288 divisors, whose sum is σ = 2712996000. Its totient is φ = 151971840.

The previous prime is 665078389. The next prime is 665078411. The reversal of 665078400 is 4870566.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (665078389) and next prime (665078411).

It is a tau number, because it is divible by the number of its divisors (288).

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 199951 + ... + 203249.

It is an arithmetic number, because the mean of its divisors is an integer number (9420125).

Almost surely, 2^665078400 is an apocalyptic number.

665078400 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 665078400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1356498000).

665078400 is an abundant number, since it is smaller than the sum of its proper divisors (2047917600).

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

665078400 is a wasteful number, since it uses less digits than its factorization.

665078400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3336 (or 3316 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 36.

The square root of 665078400 is about 25789.1139824539. The cubic root of 665078400 is about 872.8861737180.

The spelling of 665078400 in words is "six hundred sixty-five million, seventy-eight thousand, four hundred".