521257640 has 16 divisors (see below), whose sum is σ = 1172829780. Its totient is φ = 208503040.

The previous prime is 521257637. The next prime is 521257661. The reversal of 521257640 is 46752125.

It can be written as a sum of positive squares in 2 ways, for example, as 515017636 + 6240004 = 22694^2 + 2498^2 .

It is a junction number, because it is equal to n+sod(n) for n = 521257597 and 521257606.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6515681 + ... + 6515760.

Almost surely, 2^521257640 is an apocalyptic number.

It is an amenable number.

521257640 is an abundant number, since it is smaller than the sum of its proper divisors (651572140).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

521257640 is a wasteful number, since it uses less digits than its factorization.

521257640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13031452 (or 13031448 counting only the distinct ones).

The product of its (nonzero) digits is 16800, while the sum is 32.

The square root of 521257640 is about 22831.0674301488. The cubic root of 521257640 is about 804.7929151106.

The spelling of 521257640 in words is "five hundred twenty-one million, two hundred fifty-seven thousand, six hundred forty".