100505809 has 2 divisors, whose sum is σ = 100505810. Its totient is φ = 100505808.

The previous prime is 100505789. The next prime is 100505863. The reversal of 100505809 is 908505001.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 100500625 + 5184 = 10025^2 + 72^2 .

It is a cyclic number.

It is not a de Polignac number, because 100505809 - 2¹⁹ = 99981521 is a prime.

It is not a weakly prime, because it can be changed into another prime (100505609) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 50252904 + 50252905.

It is an arithmetic number, because the mean of its divisors is an integer number (50252905).

Almost surely, 2^100505809 is an apocalyptic number.

It is an amenable number.

100505809 is a deficient number, since it is larger than the sum of its proper divisors (1).

100505809 is an equidigital number, since it uses as much as digits as its factorization.

100505809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1800, while the sum is 28.

The square root of 100505809 is about 10025.2585502819. The cubic root of 100505809 is about 464.9401533956.

The spelling of 100505809 in words is "one hundred million, five hundred five thousand, eight hundred nine".