20506081 has 2 divisors, whose sum is σ = 20506082. Its totient is φ = 20506080.

The previous prime is 20506067. The next prime is 20506093. The reversal of 20506081 is 18060502.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11560000 + 8946081 = 3400^2 + 2991^2 .

It is a cyclic number.

It is not a de Polignac number, because 20506081 - 2⁵ = 20506049 is a prime.

It is a super-2 number, since 2×20506081² = 840998715957122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20506001) 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, 10253040 + 10253041.

It is an arithmetic number, because the mean of its divisors is an integer number (10253041).

Almost surely, 2^20506081 is an apocalyptic number.

It is an amenable number.

20506081 is a deficient number, since it is larger than the sum of its proper divisors (1).

20506081 is an equidigital number, since it uses as much as digits as its factorization.

20506081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 20506081 is about 4528.3640533862. The cubic root of 20506081 is about 273.7122425215.

Adding to 20506081 its reverse (18060502), we get a palindrome (38566583).

The spelling of 20506081 in words is "twenty million, five hundred six thousand, eighty-one".