505799989 has 2 divisors, whose sum is σ = 505799990. Its totient is φ = 505799988.

The previous prime is 505799977. The next prime is 505799993. The reversal of 505799989 is 989997505.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 327791025 + 178008964 = 18105^2 + 13342^2 .

It is a cyclic number.

It is not a de Polignac number, because 505799989 - 2²⁷ = 371582261 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (505799909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 252899994 + 252899995.

It is an arithmetic number, because the mean of its divisors is an integer number (252899995).

Almost surely, 2^505799989 is an apocalyptic number.

It is an amenable number.

505799989 is a deficient number, since it is larger than the sum of its proper divisors (1).

505799989 is an equidigital number, since it uses as much as digits as its factorization.

505799989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9185400, while the sum is 61.

The square root of 505799989 is about 22489.9975322364. The cubic root of 505799989 is about 796.7577047585.

The spelling of 505799989 in words is "five hundred five million, seven hundred ninety-nine thousand, nine hundred eighty-nine".