20421503 has 2 divisors, whose sum is σ = 20421504. Its totient is φ = 20421502.

The previous prime is 20421497. The next prime is 20421553. The reversal of 20421503 is 30512402.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20421503 - 2⁴ = 20421487 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20421553) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10210751 + 10210752.

It is an arithmetic number, because the mean of its divisors is an integer number (10210752).

Almost surely, 2^20421503 is an apocalyptic number.

20421503 is a deficient number, since it is larger than the sum of its proper divisors (1).

20421503 is an equidigital number, since it uses as much as digits as its factorization.

20421503 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 240, while the sum is 17.

The square root of 20421503 is about 4519.0157114133. The cubic root of 20421503 is about 273.3354122718.

Adding to 20421503 its reverse (30512402), we get a palindrome (50933905).

The spelling of 20421503 in words is "twenty million, four hundred twenty-one thousand, five hundred three".