1809865728 has 264 divisors, whose sum is σ = 5902401680. Its totient is φ = 547430400.

The previous prime is 1809865721. The next prime is 1809865789. The reversal of 1809865728 is 8275689081.

It is a tau number, because it is divible by the number of its divisors (264).

It is a super-2 number, since 2×1809865728² = 6551227906777939968, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1809865721) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3345138 + ... + 3345678.

Almost surely, 2^1809865728 is an apocalyptic number.

1809865728 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 1809865728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2951200840).

1809865728 is an abundant number, since it is smaller than the sum of its proper divisors (4092535952).

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

1809865728 is a wasteful number, since it uses less digits than its factorization.

1809865728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 592 (or 557 counting only the distinct ones).

The product of its (nonzero) digits is 1935360, while the sum is 54.

The square root of 1809865728 is about 42542.5167097575. The cubic root of 1809865728 is about 1218.6587714909.

The spelling of 1809865728 in words is "one billion, eight hundred nine million, eight hundred sixty-five thousand, seven hundred twenty-eight".