20902081 has 2 divisors, whose sum is σ = 20902082. Its totient is φ = 20902080.

The previous prime is 20902073. The next prime is 20902103. The reversal of 20902081 is 18020902.

It is an a-pointer prime, because the next prime (20902103) can be obtained adding 20902081 to its sum of digits (22).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16679056 + 4223025 = 4084^2 + 2055^2 .

It is a cyclic number.

It is not a de Polignac number, because 20902081 - 2³ = 20902073 is a prime.

It is a super-2 number, since 2×20902081² = 873793980261122, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20902031) 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, 10451040 + 10451041.

It is an arithmetic number, because the mean of its divisors is an integer number (10451041).

Almost surely, 2^20902081 is an apocalyptic number.

It is an amenable number.

20902081 is a deficient number, since it is larger than the sum of its proper divisors (1).

20902081 is an equidigital number, since it uses as much as digits as its factorization.

20902081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 288, while the sum is 22.

The square root of 20902081 is about 4571.8793728619. The cubic root of 20902081 is about 275.4629381536.

Adding to 20902081 its reverse (18020902), we get a palindrome (38922983).

The spelling of 20902081 in words is "twenty million, nine hundred two thousand, eighty-one".