1820639805 has 16 divisors (see below), whose sum is σ = 2913584640. Its totient is φ = 970820928.

The previous prime is 1820639771. The next prime is 1820639813. The reversal of 1820639805 is 5089360281.

It is not a de Polignac number, because 1820639805 - 2¹¹ = 1820637757 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 109044 + ... + 124626.

It is an arithmetic number, because the mean of its divisors is an integer number (182099040).

Almost surely, 2^1820639805 is an apocalyptic number.

1820639805 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1820639805 is a deficient number, since it is larger than the sum of its proper divisors (1092944835).

1820639805 is a wasteful number, since it uses less digits than its factorization.

1820639805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23380.

The product of its (nonzero) digits is 103680, while the sum is 42.

The square root of 1820639805 is about 42668.9559867593. The cubic root of 1820639805 is about 1221.0722019549.

The spelling of 1820639805 in words is "one billion, eight hundred twenty million, six hundred thirty-nine thousand, eight hundred five".