521235232421 has 4 divisors (see below), whose sum is σ = 525039869292. Its totient is φ = 517430595552.

The previous prime is 521235232393. The next prime is 521235232433. The reversal of 521235232421 is 124232532125.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 445562925025 + 75672307396 = 667505^2 + 275086^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-521235232421 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (521235235421) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1902318230 + ... + 1902318503.

It is an arithmetic number, because the mean of its divisors is an integer number (131259967323).

Almost surely, 2^521235232421 is an apocalyptic number.

It is an amenable number.

521235232421 is a deficient number, since it is larger than the sum of its proper divisors (3804636871).

521235232421 is a wasteful number, since it uses less digits than its factorization.

521235232421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3804636870.

The product of its digits is 28800, while the sum is 32.

Adding to 521235232421 its reverse (124232532125), we get a palindrome (645467764546).

The spelling of 521235232421 in words is "five hundred twenty-one billion, two hundred thirty-five million, two hundred thirty-two thousand, four hundred twenty-one".