521666245 has 4 divisors (see below), whose sum is σ = 625999500. Its totient is φ = 417332992.

The previous prime is 521666213. The next prime is 521666269. The reversal of 521666245 is 542666125.

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 175483009 + 346183236 = 13247^2 + 18606^2 .

It is a cyclic number.

It is not a de Polignac number, because 521666245 - 2⁵ = 521666213 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 52166620 + ... + 52166629.

It is an arithmetic number, because the mean of its divisors is an integer number (156499875).

Almost surely, 2^521666245 is an apocalyptic number.

It is an amenable number.

521666245 is a deficient number, since it is larger than the sum of its proper divisors (104333255).

521666245 is a wasteful number, since it uses less digits than its factorization.

521666245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 104333254.

The product of its digits is 86400, while the sum is 37.

The square root of 521666245 is about 22840.0141199606. The cubic root of 521666245 is about 805.0031480144.

The spelling of 521666245 in words is "five hundred twenty-one million, six hundred sixty-six thousand, two hundred forty-five".