4221520621 has 2 divisors, whose sum is σ = 4221520622. Its totient is φ = 4221520620.

The previous prime is 4221520619. The next prime is 4221520637. The reversal of 4221520621 is 1260251224.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 3340262025 + 881258596 = 57795^2 + 29686^2 .

It is a cyclic number.

It is not a de Polignac number, because 4221520621 - 2¹ = 4221520619 is a prime.

Together with 4221520619, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (4221527621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2110760310 + 2110760311.

It is an arithmetic number, because the mean of its divisors is an integer number (2110760311).

Almost surely, 2^4221520621 is an apocalyptic number.

It is an amenable number.

4221520621 is a deficient number, since it is larger than the sum of its proper divisors (1).

4221520621 is an equidigital number, since it uses as much as digits as its factorization.

4221520621 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 4221520621 is about 64973.2300336069. The cubic root of 4221520621 is about 1616.1796658648.

Adding to 4221520621 its reverse (1260251224), we get a palindrome (5481771845).

The spelling of 4221520621 in words is "four billion, two hundred twenty-one million, five hundred twenty thousand, six hundred twenty-one".