866261520 has 320 divisors, whose sum is σ = 3265505280. Its totient is φ = 210124800.

The previous prime is 866261519. The next prime is 866261569. The reversal of 866261520 is 25162668.

866261520 is a `hidden beast` number, since 8 + 6 + 626 + 1 + 5 + 20 = 666.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

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 63 ways as a sum of consecutive naturals, for example, 1137940 + ... + 1138700.

It is an arithmetic number, because the mean of its divisors is an integer number (10204704).

Almost surely, 2^866261520 is an apocalyptic number.

866261520 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 866261520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1632752640).

866261520 is an abundant number, since it is smaller than the sum of its proper divisors (2399243760).

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

866261520 is a wasteful number, since it uses less digits than its factorization.

866261520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 831 (or 819 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

The square root of 866261520 is about 29432.3210093937. The cubic root of 866261520 is about 953.2709116328.

The spelling of 866261520 in words is "eight hundred sixty-six million, two hundred sixty-one thousand, five hundred twenty".