1866217860 has 384 divisors, whose sum is σ = 6604416000. Its totient is φ = 434294784.

The previous prime is 1866217853. The next prime is 1866217901. The reversal of 1866217860 is 687126681.

It is a happy number.

1866217860 is a `hidden beast` number, since 18 + 6 + 621 + 7 + 8 + 6 + 0 = 666.

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

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, 18118569 + ... + 18118671.

It is an arithmetic number, because the mean of its divisors is an integer number (17199000).

Almost surely, 2^1866217860 is an apocalyptic number.

1866217860 is a gapful number since it is divisible by the number (10) 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 1866217860, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3302208000).

1866217860 is an abundant number, since it is smaller than the sum of its proper divisors (4738198140).

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

1866217860 is a wasteful number, since it uses less digits than its factorization.

1866217860 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 252 (or 244 counting only the distinct ones).

The product of its (nonzero) digits is 193536, while the sum is 45.

The square root of 1866217860 is about 43199.7437492400. The cubic root of 1866217860 is about 1231.1778129065.

It can be divided in two parts, 186621 and 7860, that added together give a 4-th power (194481 = 21⁴).

The spelling of 1866217860 in words is "one billion, eight hundred sixty-six million, two hundred seventeen thousand, eight hundred sixty".