666091440 has 240 divisors, whose sum is σ = 2571049728. Its totient is φ = 151386624.

The previous prime is 666091429. The next prime is 666091441. The reversal of 666091440 is 44190666.

It is a tau number, because it is divible by the number of its divisors (240).

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

It is a junction number, because it is equal to n+sod(n) for n = 666091395 and 666091404.

It is not an unprimeable number, because it can be changed into a prime (666091441) by changing a digit.

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 47 ways as a sum of consecutive naturals, for example, 1426087 + ... + 1426553.

Almost surely, 2^666091440 is an apocalyptic number.

666091440 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 666091440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1285524864).

666091440 is an abundant number, since it is smaller than the sum of its proper divisors (1904958288).

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

666091440 is a wasteful number, since it uses less digits than its factorization.

666091440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 776 (or 767 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 36.

The square root of 666091440 is about 25808.7473543371. The cubic root of 666091440 is about 873.3291390484.

The spelling of 666091440 in words is "six hundred sixty-six million, ninety-one thousand, four hundred forty".