501016561 has 4 divisors (see below), whose sum is σ = 501245172. Its totient is φ = 500787952.

The previous prime is 501016517. The next prime is 501016577. The reversal of 501016561 is 165610105.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 165610105 = 5 ⋅33122021.

It can be written as a sum of positive squares in 2 ways, for example, as 314530225 + 186486336 = 17735^2 + 13656^2 .

It is a cyclic number.

It is not a de Polignac number, because 501016561 - 2¹¹ = 501014513 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (501016591) 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, 110986 + ... + 115411.

It is an arithmetic number, because the mean of its divisors is an integer number (125311293).

Almost surely, 2^501016561 is an apocalyptic number.

It is an amenable number.

501016561 is a deficient number, since it is larger than the sum of its proper divisors (228611).

501016561 is a wasteful number, since it uses less digits than its factorization.

501016561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 228610.

The product of its (nonzero) digits is 900, while the sum is 25.

The square root of 501016561 is about 22383.3992279993. The cubic root of 501016561 is about 794.2380585257.

Adding to 501016561 its reverse (165610105), we get a palindrome (666626666).

The spelling of 501016561 in words is "five hundred one million, sixteen thousand, five hundred sixty-one".