501606661 has 4 divisors (see below), whose sum is σ = 506045772. Its totient is φ = 497167552.

The previous prime is 501606643. The next prime is 501606671. The reversal of 501606661 is 166606105.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 218862436 + 282744225 = 14794^2 + 16815^2 .

It is a cyclic number.

It is not a de Polignac number, because 501606661 - 2¹¹ = 501604613 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (501606671) 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, 2219386 + ... + 2219611.

It is an arithmetic number, because the mean of its divisors is an integer number (126511443).

Almost surely, 2^501606661 is an apocalyptic number.

It is an amenable number.

501606661 is a deficient number, since it is larger than the sum of its proper divisors (4439111).

501606661 is a wasteful number, since it uses less digits than its factorization.

501606661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4439110.

The product of its (nonzero) digits is 6480, while the sum is 31.

The square root of 501606661 is about 22396.5769929246. The cubic root of 501606661 is about 794.5497554705.

The spelling of 501606661 in words is "five hundred one million, six hundred six thousand, six hundred sixty-one".