20987237 has 2 divisors, whose sum is σ = 20987238. Its totient is φ = 20987236.

The previous prime is 20987227. The next prime is 20987243. The reversal of 20987237 is 73278902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20124196 + 863041 = 4486^2 + 929^2 .

It is a cyclic number.

It is not a de Polignac number, because 20987237 - 2¹² = 20983141 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20987237.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20987227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10493618 + 10493619.

It is an arithmetic number, because the mean of its divisors is an integer number (10493619).

Almost surely, 2^20987237 is an apocalyptic number.

It is an amenable number.

20987237 is a deficient number, since it is larger than the sum of its proper divisors (1).

20987237 is an equidigital number, since it uses as much as digits as its factorization.

20987237 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 42336, while the sum is 38.

The square root of 20987237 is about 4581.1829258391. The cubic root of 20987237 is about 275.8365140108.

The spelling of 20987237 in words is "twenty million, nine hundred eighty-seven thousand, two hundred thirty-seven".