1801581620 has 18 divisors (see below), whose sum is σ = 3783720066. Its totient is φ = 720556720.

The previous prime is 1801581563. The next prime is 1801581623. The reversal of 1801581620 is 261851081.

It can be written as a sum of positive squares in only one way, i.e., 1441265296 + 360316324 = 37964^2 + 18982^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1801581623) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 185075 + ... + 194565.

Almost surely, 2^1801581620 is an apocalyptic number.

1801581620 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1801581620 is an abundant number, since it is smaller than the sum of its proper divisors (1982138446).

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

1801581620 is an frugal number, since it uses more digits than its factorization.

1801581620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18991 (or 9498 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 32.

The square root of 1801581620 is about 42445.0423489010. The cubic root of 1801581620 is about 1216.7965811942.

The spelling of 1801581620 in words is "one billion, eight hundred one million, five hundred eighty-one thousand, six hundred twenty".