505721 has 4 divisors (see below), whose sum is σ = 507792. Its totient is φ = 503652.

The previous prime is 505711. The next prime is 505727. The reversal of 505721 is 127505.

505721 is nontrivially palindromic in base 14.

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.

It is a cyclic number.

It is not a de Polignac number, because 505721 - 2⁶ = 505657 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 505693 and 505702.

It is not an unprimeable number, because it can be changed into a prime (505727) 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, 611 + ... + 1176.

It is an arithmetic number, because the mean of its divisors is an integer number (126948).

2⁵⁰⁵⁷²¹ is an apocalyptic number.

It is an amenable number.

505721 is a deficient number, since it is larger than the sum of its proper divisors (2071).

505721 is a wasteful number, since it uses less digits than its factorization.

505721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2070.

The product of its (nonzero) digits is 350, while the sum is 20.

The square root of 505721 is about 711.1406330677. The cubic root of 505721 is about 79.6716226986.

The spelling of 505721 in words is "five hundred five thousand, seven hundred twenty-one".