1821866640 has 160 divisors (see below), whose sum is σ = 6292740096. Its totient is φ = 432238080.

The previous prime is 1821866609. The next prime is 1821866663. The reversal of 1821866640 is 466681281.

It is a junction number, because it is equal to n+sod(n) for n = 1821866592 and 1821866601.

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, 116739 + ... + 131421.

Almost surely, 2^1821866640 is an apocalyptic number.

1821866640 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 1821866640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3146370048).

1821866640 is an abundant number, since it is smaller than the sum of its proper divisors (4470873456).

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

1821866640 is a wasteful number, since it uses less digits than its factorization.

1821866640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14757 (or 14751 counting only the distinct ones).

The product of its (nonzero) digits is 110592, while the sum is 42.

The square root of 1821866640 is about 42683.3297670179. The cubic root of 1821866640 is about 1221.3464128394.

The spelling of 1821866640 in words is "one billion, eight hundred twenty-one million, eight hundred sixty-six thousand, six hundred forty".