1821218520 has 128 divisors (see below), whose sum is σ = 5972797440. Its totient is φ = 440586240.

The previous prime is 1821218491. The next prime is 1821218537. The reversal of 1821218520 is 258121281.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

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, 800104 + ... + 802376.

It is an arithmetic number, because the mean of its divisors is an integer number (46662480).

Almost surely, 2^1821218520 is an apocalyptic number.

1821218520 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 1821218520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2986398720).

1821218520 is an abundant number, since it is smaller than the sum of its proper divisors (4151578920).

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

1821218520 is a wasteful number, since it uses less digits than its factorization.

1821218520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2905 (or 2901 counting only the distinct ones).

The product of its (nonzero) digits is 2560, while the sum is 30.

The square root of 1821218520 is about 42675.7369004918. The cubic root of 1821218520 is about 1221.2015663570.

The spelling of 1821218520 in words is "one billion, eight hundred twenty-one million, two hundred eighteen thousand, five hundred twenty".