20807081 has 2 divisors, whose sum is σ = 20807082. Its totient is φ = 20807080.

The previous prime is 20807077. The next prime is 20807089. The reversal of 20807081 is 18070802.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20025625 + 781456 = 4475^2 + 884^2 .

It is a cyclic number.

It is not a de Polignac number, because 20807081 - 2² = 20807077 is a prime.

It is a super-2 number, since 2×20807081² = 865869239481122, which contains 22 as substring.

It is a zygodrome in base 3.

It is a self number, because there is not a number n which added to its sum of digits gives 20807081.

It is not a weakly prime, because it can be changed into another prime (20807089) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10403540 + 10403541.

It is an arithmetic number, because the mean of its divisors is an integer number (10403541).

Almost surely, 2^20807081 is an apocalyptic number.

It is an amenable number.

20807081 is a deficient number, since it is larger than the sum of its proper divisors (1).

20807081 is an equidigital number, since it uses as much as digits as its factorization.

20807081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 896, while the sum is 26.

The square root of 20807081 is about 4561.4779403172. The cubic root of 20807081 is about 275.0449777672.

Adding to 20807081 its reverse (18070802), we get a palindrome (38877883).

The spelling of 20807081 in words is "twenty million, eight hundred seven thousand, eighty-one".