20988881 has 2 divisors, whose sum is σ = 20988882. Its totient is φ = 20988880.

The previous prime is 20988853. The next prime is 20988893. The reversal of 20988881 is 18888902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12138256 + 8850625 = 3484^2 + 2975^2 .

It is a cyclic number.

It is not a de Polignac number, because 20988881 - 2¹⁸ = 20726737 is a prime.

It is a super-2 number, since 2×20988881² = 881066251264322, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20988481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10494440 + 10494441.

It is an arithmetic number, because the mean of its divisors is an integer number (10494441).

Almost surely, 2^20988881 is an apocalyptic number.

It is an amenable number.

20988881 is a deficient number, since it is larger than the sum of its proper divisors (1).

20988881 is an equidigital number, since it uses as much as digits as its factorization.

20988881 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 73728, while the sum is 44.

The square root of 20988881 is about 4581.3623519648. The cubic root of 20988881 is about 275.8437162196.

The spelling of 20988881 in words is "twenty million, nine hundred eighty-eight thousand, eight hundred eighty-one".