521256551 has 2 divisors, whose sum is σ = 521256552. Its totient is φ = 521256550.

The previous prime is 521256509. The next prime is 521256553. The reversal of 521256551 is 155652125.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 521256551 - 2⁶ = 521256487 is a prime.

It is a Sophie Germain prime.

Together with 521256553, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (521256553) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 260628275 + 260628276.

It is an arithmetic number, because the mean of its divisors is an integer number (260628276).

Almost surely, 2^521256551 is an apocalyptic number.

521256551 is a deficient number, since it is larger than the sum of its proper divisors (1).

521256551 is an equidigital number, since it uses as much as digits as its factorization.

521256551 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15000, while the sum is 32.

The square root of 521256551 is about 22831.0435810543. The cubic root of 521256551 is about 804.7923546583.

The spelling of 521256551 in words is "five hundred twenty-one million, two hundred fifty-six thousand, five hundred fifty-one".