20887621 has 2 divisors, whose sum is σ = 20887622. Its totient is φ = 20887620.

The previous prime is 20887613. The next prime is 20887649. The reversal of 20887621 is 12678802.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19483396 + 1404225 = 4414^2 + 1185^2 .

It is a cyclic number.

It is not a de Polignac number, because 20887621 - 2³ = 20887613 is a prime.

It is a super-2 number, since 2×20887621² = 872585422079282, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20887651) 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, 10443810 + 10443811.

It is an arithmetic number, because the mean of its divisors is an integer number (10443811).

Almost surely, 2^20887621 is an apocalyptic number.

It is an amenable number.

20887621 is a deficient number, since it is larger than the sum of its proper divisors (1).

20887621 is an equidigital number, since it uses as much as digits as its factorization.

20887621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10752, while the sum is 34.

The square root of 20887621 is about 4570.2976927111. The cubic root of 20887621 is about 275.3994020084.

The spelling of 20887621 in words is "twenty million, eight hundred eighty-seven thousand, six hundred twenty-one".