666109440 has 320 divisors, whose sum is σ = 2474841600. Its totient is φ = 169500672.

The previous prime is 666109373. The next prime is 666109501. The reversal of 666109440 is 44901666.

It is a tau number, because it is divible by the number of its divisors (320).

It is a super-2 number, since 2×666109440² = 887403572114227200, which contains 22 as substring.

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 = 666109395 and 666109404.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1589551 + ... + 1589969.

It is an arithmetic number, because the mean of its divisors is an integer number (7733880).

Almost surely, 2^666109440 is an apocalyptic number.

666109440 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 666109440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1237420800).

666109440 is an abundant number, since it is smaller than the sum of its proper divisors (1808732160).

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

666109440 is a wasteful number, since it uses less digits than its factorization.

666109440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 474 (or 452 counting only the distinct ones).

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

The square root of 666109440 is about 25809.0960709592. The cubic root of 666109440 is about 873.3370057276.

The spelling of 666109440 in words is "six hundred sixty-six million, one hundred nine thousand, four hundred forty".