1805681890 has 8 divisors (see below), whose sum is σ = 3250227420. Its totient is φ = 722272752.

The previous prime is 1805681887. The next prime is 1805681921. The reversal of 1805681890 is 981865081.

It can be written as a sum of positive squares in 2 ways, for example, as 1804635361 + 1046529 = 42481^2 + 1023^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a self number, because there is not a number n which added to its sum of digits gives 1805681890.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 90284085 + ... + 90284104.

Almost surely, 2^1805681890 is an apocalyptic number.

1805681890 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1805681890 is a deficient number, since it is larger than the sum of its proper divisors (1444545530).

1805681890 is a wasteful number, since it uses less digits than its factorization.

1805681890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 180568196.

The product of its (nonzero) digits is 138240, while the sum is 46.

The square root of 1805681890 is about 42493.3158273157. The cubic root of 1805681890 is about 1217.7189955560.

The spelling of 1805681890 in words is "one billion, eight hundred five million, six hundred eighty-one thousand, eight hundred ninety".