421313521 has 4 divisors (see below), whose sum is σ = 425485044. Its totient is φ = 417142000.

The previous prime is 421313509. The next prime is 421313573. The reversal of 421313521 is 125313124.

It is a happy number.

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 367143921 + 54169600 = 19161^2 + 7360^2 .

It is a cyclic number.

It is not a de Polignac number, because 421313521 - 2⁵ = 421313489 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 421313492 and 421313501.

It is not an unprimeable number, because it can be changed into a prime (421317521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2085610 + ... + 2085811.

It is an arithmetic number, because the mean of its divisors is an integer number (106371261).

Almost surely, 2^421313521 is an apocalyptic number.

It is an amenable number.

421313521 is a deficient number, since it is larger than the sum of its proper divisors (4171523).

421313521 is a wasteful number, since it uses less digits than its factorization.

421313521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4171522.

The product of its digits is 720, while the sum is 22.

The square root of 421313521 is about 20525.9231461097. The cubic root of 421313521 is about 749.6671239836.

Adding to 421313521 its reverse (125313124), we get a palindrome (546626645).

The spelling of 421313521 in words is "four hundred twenty-one million, three hundred thirteen thousand, five hundred twenty-one".