521404621 has 2 divisors, whose sum is σ = 521404622. Its totient is φ = 521404620.

The previous prime is 521404591. The next prime is 521404633. The reversal of 521404621 is 126404125.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 367297225 + 154107396 = 19165^2 + 12414^2 .

It is a cyclic number.

It is not a de Polignac number, because 521404621 - 2¹³ = 521396429 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (521404321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 260702310 + 260702311.

It is an arithmetic number, because the mean of its divisors is an integer number (260702311).

Almost surely, 2^521404621 is an apocalyptic number.

It is an amenable number.

521404621 is a deficient number, since it is larger than the sum of its proper divisors (1).

521404621 is an equidigital number, since it uses as much as digits as its factorization.

521404621 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1920, while the sum is 25.

The square root of 521404621 is about 22834.2860847455. The cubic root of 521404621 is about 804.8685515087.

Adding to 521404621 its reverse (126404125), we get a palindrome (647808746).

The spelling of 521404621 in words is "five hundred twenty-one million, four hundred four thousand, six hundred twenty-one".