1821311028 has 144 divisors (see below), whose sum is σ = 5016816000. Its totient is φ = 571253760.

The previous prime is 1821310991. The next prime is 1821311029. The reversal of 1821311028 is 8201131281.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a junction number, because it is equal to n+sod(n) for n = 1821310992 and 1821311010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1821311029) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 4056148 + ... + 4056596.

It is an arithmetic number, because the mean of its divisors is an integer number (34839000).

Almost surely, 2^1821311028 is an apocalyptic number.

1821311028 is a gapful number since it is divisible by the number (18) 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 1821311028, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2508408000).

1821311028 is an abundant number, since it is smaller than the sum of its proper divisors (3195504972).

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

1821311028 is a wasteful number, since it uses less digits than its factorization.

1821311028 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 579 (or 548 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 27.

The square root of 1821311028 is about 42676.8207344455. The cubic root of 1821311028 is about 1221.2222428072. Note that the first 4 decimals are identical.

It can be divided in two parts, 18213 and 11028, that added together give a square (29241 = 171²).

The spelling of 1821311028 in words is "one billion, eight hundred twenty-one million, three hundred eleven thousand, twenty-eight".