521661673 has 8 divisors (see below), whose sum is σ = 562628808. Its totient is φ = 480814464.

The previous prime is 521661671. The next prime is 521661697. The reversal of 521661673 is 376166125.

It can be written as a sum of positive squares in 4 ways, for example, as 154057744 + 367603929 = 12412^2 + 19173^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 521661673 - 2¹ = 521661671 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (521661671) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20836 + ... + 38437.

It is an arithmetic number, because the mean of its divisors is an integer number (70328601).

Almost surely, 2^521661673 is an apocalyptic number.

It is an amenable number.

521661673 is a deficient number, since it is larger than the sum of its proper divisors (40967135).

521661673 is a wasteful number, since it uses less digits than its factorization.

521661673 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59963.

The product of its digits is 45360, while the sum is 37.

The square root of 521661673 is about 22839.9140322375. The cubic root of 521661673 is about 805.0007962648. Note that the first 3 decimals are identical.

The spelling of 521661673 in words is "five hundred twenty-one million, six hundred sixty-one thousand, six hundred seventy-three".