20421187 has 2 divisors, whose sum is σ = 20421188. Its totient is φ = 20421186.

The previous prime is 20421179. The next prime is 20421209. The reversal of 20421187 is 78112402.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20421187 - 2³ = 20421179 is a prime.

It is not a weakly prime, because it can be changed into another prime (20421287) 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, 10210593 + 10210594.

It is an arithmetic number, because the mean of its divisors is an integer number (10210594).

Almost surely, 2^20421187 is an apocalyptic number.

20421187 is a deficient number, since it is larger than the sum of its proper divisors (1).

20421187 is an equidigital number, since it uses as much as digits as its factorization.

20421187 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 896, while the sum is 25.

The square root of 20421187 is about 4518.9807479121. The cubic root of 20421187 is about 273.3340024109.

Adding to 20421187 its reverse (78112402), we get a palindrome (98533589).

The spelling of 20421187 in words is "twenty million, four hundred twenty-one thousand, one hundred eighty-seven".