521402561 has 2 divisors, whose sum is σ = 521402562. Its totient is φ = 521402560.

The previous prime is 521402527. The next prime is 521402569. The reversal of 521402561 is 165204125.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 480442561 + 40960000 = 21919^2 + 6400^2 .

It is a cyclic number.

It is not a de Polignac number, because 521402561 - 2¹⁰ = 521401537 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 521402561.

It is not a weakly prime, because it can be changed into another prime (521402569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 260701280 + 260701281.

It is an arithmetic number, because the mean of its divisors is an integer number (260701281).

Almost surely, 2^521402561 is an apocalyptic number.

It is an amenable number.

521402561 is a deficient number, since it is larger than the sum of its proper divisors (1).

521402561 is an equidigital number, since it uses as much as digits as its factorization.

521402561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2400, while the sum is 26.

The square root of 521402561 is about 22834.2409770940. The cubic root of 521402561 is about 804.8674915312.

Adding to 521402561 its reverse (165204125), we get a palindrome (686606686).

The spelling of 521402561 in words is "five hundred twenty-one million, four hundred two thousand, five hundred sixty-one".