521279989 has 2 divisors, whose sum is σ = 521279990. Its totient is φ = 521279988.

The previous prime is 521279987. The next prime is 521280049. The reversal of 521279989 is 989972125.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 399000625 + 122279364 = 19975^2 + 11058^2 .

It is a cyclic number.

It is not a de Polignac number, because 521279989 - 2¹ = 521279987 is a prime.

Together with 521279987, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (521279987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 260639994 + 260639995.

It is an arithmetic number, because the mean of its divisors is an integer number (260639995).

Almost surely, 2^521279989 is an apocalyptic number.

It is an amenable number.

521279989 is a deficient number, since it is larger than the sum of its proper divisors (1).

521279989 is an equidigital number, since it uses as much as digits as its factorization.

521279989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 816480, while the sum is 52.

The square root of 521279989 is about 22831.5568676339. The cubic root of 521279989 is about 804.8044168188.

The spelling of 521279989 in words is "five hundred twenty-one million, two hundred seventy-nine thousand, nine hundred eighty-nine".