521256647 has 2 divisors, whose sum is σ = 521256648. Its totient is φ = 521256646.

The previous prime is 521256623. The next prime is 521256679. The reversal of 521256647 is 746652125.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 521256647 - 2²⁶ = 454147783 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 521256647.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (521256347) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 260628323 + 260628324.

It is an arithmetic number, because the mean of its divisors is an integer number (260628324).

Almost surely, 2^521256647 is an apocalyptic number.

521256647 is a deficient number, since it is larger than the sum of its proper divisors (1).

521256647 is an equidigital number, since it uses as much as digits as its factorization.

521256647 is an evil number, because the sum of its binary digits is even.

The product of its digits is 100800, while the sum is 38.

The square root of 521256647 is about 22831.0456834548. The cubic root of 521256647 is about 804.7924040646.

The spelling of 521256647 in words is "five hundred twenty-one million, two hundred fifty-six thousand, six hundred forty-seven".