505978961 has 2 divisors, whose sum is σ = 505978962. Its totient is φ = 505978960.

The previous prime is 505978943. The next prime is 505979021. The reversal of 505978961 is 169879505.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 355548736 + 150430225 = 18856^2 + 12265^2 .

It is a cyclic number.

It is not a de Polignac number, because 505978961 - 2¹⁸ = 505716817 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (505978661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 252989480 + 252989481.

It is an arithmetic number, because the mean of its divisors is an integer number (252989481).

Almost surely, 2^505978961 is an apocalyptic number.

It is an amenable number.

505978961 is a deficient number, since it is larger than the sum of its proper divisors (1).

505978961 is an equidigital number, since it uses as much as digits as its factorization.

505978961 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 680400, while the sum is 50.

The square root of 505978961 is about 22493.9761047263. The cubic root of 505978961 is about 796.8516684513.

The spelling of 505978961 in words is "five hundred five million, nine hundred seventy-eight thousand, nine hundred sixty-one".