421211521 has 2 divisors, whose sum is σ = 421211522. Its totient is φ = 421211520.

The previous prime is 421211519. The next prime is 421211537. The reversal of 421211521 is 125112124.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 406465921 + 14745600 = 20161^2 + 3840^2 .

It is a cyclic number.

It is not a de Polignac number, because 421211521 - 2¹ = 421211519 is a prime.

Together with 421211519, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (421211501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 210605760 + 210605761.

It is an arithmetic number, because the mean of its divisors is an integer number (210605761).

Almost surely, 2^421211521 is an apocalyptic number.

It is an amenable number.

421211521 is a deficient number, since it is larger than the sum of its proper divisors (1).

421211521 is an equidigital number, since it uses as much as digits as its factorization.

421211521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 160, while the sum is 19.

The square root of 421211521 is about 20523.4383327940. The cubic root of 421211521 is about 749.6066209659.

Adding to 421211521 its reverse (125112124), we get a palindrome (546323645).

The spelling of 421211521 in words is "four hundred twenty-one million, two hundred eleven thousand, five hundred twenty-one".