866557440 has 480 divisors, whose sum is σ = 3574771200. Its totient is φ = 197074944.

The previous prime is 866557429. The next prime is 866557451. The reversal of 866557440 is 44755668.

It is an interprime number because it is at equal distance from previous prime (866557429) and next prime (866557451).

It is a tau number, because it is divible by the number of its divisors (480).

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 4354461 + ... + 4354659.

It is an arithmetic number, because the mean of its divisors is an integer number (7447440).

Almost surely, 2^866557440 is an apocalyptic number.

866557440 is a gapful number since it is divisible by the number (80) 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 866557440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1787385600).

866557440 is an abundant number, since it is smaller than the sum of its proper divisors (2708213760).

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

866557440 is an equidigital number, since it uses as much as digits as its factorization.

866557440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 244 (or 216 counting only the distinct ones).

The product of its (nonzero) digits is 806400, while the sum is 45.

The square root of 866557440 is about 29437.3477066124. The cubic root of 866557440 is about 953.3794469139.

The spelling of 866557440 in words is "eight hundred sixty-six million, five hundred fifty-seven thousand, four hundred forty".