20818481 has 2 divisors, whose sum is σ = 20818482. Its totient is φ = 20818480.

The previous prime is 20818477. The next prime is 20818487. The reversal of 20818481 is 18481802.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19280881 + 1537600 = 4391^2 + 1240^2 .

It is a cyclic number.

It is not a de Polignac number, because 20818481 - 2² = 20818477 is a prime.

It is a super-2 number, since 2×20818481² = 866818302294722, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20818487) 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, 10409240 + 10409241.

It is an arithmetic number, because the mean of its divisors is an integer number (10409241).

Almost surely, 2^20818481 is an apocalyptic number.

It is an amenable number.

20818481 is a deficient number, since it is larger than the sum of its proper divisors (1).

20818481 is an equidigital number, since it uses as much as digits as its factorization.

20818481 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4096, while the sum is 32.

The square root of 20818481 is about 4562.7273641979. The cubic root of 20818481 is about 275.0952000975.

The spelling of 20818481 in words is "twenty million, eight hundred eighteen thousand, four hundred eighty-one".