1816821760 has 128 divisors (see below), whose sum is σ = 4701218760. Its totient is φ = 670040064.

The previous prime is 1816821749. The next prime is 1816821761. The reversal of 1816821760 is 671286181.

It can be written as a sum of positive squares in 4 ways, for example, as 648822784 + 1167998976 = 25472^2 + 34176^2 .

It is a tau number, because it is divible by the number of its divisors (128).

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1816821761) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2129494 + ... + 2130346.

Almost surely, 2^1816821760 is an apocalyptic number.

1816821760 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 1816821760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2350609380).

1816821760 is an abundant number, since it is smaller than the sum of its proper divisors (2884397000).

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

1816821760 is an frugal number, since it uses more digits than its factorization.

1816821760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 901 (or 873 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 40.

The square root of 1816821760 is about 42624.1921917589. The cubic root of 1816821760 is about 1220.2180386075.

The spelling of 1816821760 in words is "one billion, eight hundred sixteen million, eight hundred twenty-one thousand, seven hundred sixty".