20421253 has 2 divisors, whose sum is σ = 20421254. Its totient is φ = 20421252.

The previous prime is 20421251. The next prime is 20421277. The reversal of 20421253 is 35212402.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20088324 + 332929 = 4482^2 + 577^2 .

It is a cyclic number.

It is not a de Polignac number, because 20421253 - 2¹ = 20421251 is a prime.

Together with 20421251, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 20421253.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20421251) 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, 10210626 + 10210627.

It is an arithmetic number, because the mean of its divisors is an integer number (10210627).

Almost surely, 2^20421253 is an apocalyptic number.

It is an amenable number.

20421253 is a deficient number, since it is larger than the sum of its proper divisors (1).

20421253 is an equidigital number, since it uses as much as digits as its factorization.

20421253 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 480, while the sum is 19.

The square root of 20421253 is about 4518.9880504378. The cubic root of 20421253 is about 273.3342968768.

Adding to 20421253 its reverse (35212402), we get a palindrome (55633655).

The spelling of 20421253 in words is "twenty million, four hundred twenty-one thousand, two hundred fifty-three".