866123857473840 has 640 divisors, whose sum is σ = 3486155291781120. Its totient is φ = 193569595195392.

The previous prime is 866123857473821. The next prime is 866123857473859. The reversal of 866123857473840 is 48374758321668.

866123857473840 is a `hidden beast` number, since 8 + 6 + 6 + 1 + 2 + 3 + 8 + 574 + 7 + 3 + 8 + 40 = 666.

It is an interprime number because it is at equal distance from previous prime (866123857473821) and next prime (866123857473859).

It is a Harshad number since it is a multiple of its sum of digits (72).

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 118173592 + ... + 125288648.

It is an arithmetic number, because the mean of its divisors is an integer number (5447117643408).

Almost surely, 2^{866123857473840} is an apocalyptic number.

866123857473840 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 866123857473840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1743077645890560).

866123857473840 is an abundant number, since it is smaller than the sum of its proper divisors (2620031434307280).

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

866123857473840 is a wasteful number, since it uses less digits than its factorization.

866123857473840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7115266 (or 7115254 counting only the distinct ones).

The product of its (nonzero) digits is 1300561920, while the sum is 72.

The spelling of 866123857473840 in words is "eight hundred sixty-six trillion, one hundred twenty-three billion, eight hundred fifty-seven million, four hundred seventy-three thousand, eight hundred forty".