505138261 has 4 divisors (see below), whose sum is σ = 505211392. Its totient is φ = 505065132.

The previous prime is 505138247. The next prime is 505138297. The reversal of 505138261 is 162831505.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 162831505 = 5 ⋅32566301.

It is a cyclic number.

It is not a de Polignac number, because 505138261 - 2⁵ = 505138229 is a prime.

It is a super-2 number, since 2×505138261² = 510329325452208242, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (505138201) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24981 + ... + 40426.

It is an arithmetic number, because the mean of its divisors is an integer number (126302848).

Almost surely, 2^505138261 is an apocalyptic number.

It is an amenable number.

505138261 is a deficient number, since it is larger than the sum of its proper divisors (73131).

505138261 is an equidigital number, since it uses as much as digits as its factorization.

505138261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73130.

The product of its (nonzero) digits is 7200, while the sum is 31.

The square root of 505138261 is about 22475.2811105890. The cubic root of 505138261 is about 796.4100924047.

Adding to 505138261 its reverse (162831505), we get a palindrome (667969766).

The spelling of 505138261 in words is "five hundred five million, one hundred thirty-eight thousand, two hundred sixty-one".