20042081 has 4 divisors (see below), whose sum is σ = 20065812. Its totient is φ = 20018352.

The previous prime is 20042059. The next prime is 20042101. The reversal of 20042081 is 18024002.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18024002 = 2 ⋅9012001.

It can be written as a sum of positive squares in 2 ways, for example, as 10182481 + 9859600 = 3191^2 + 3140^2 .

It is a cyclic number.

It is not a de Polignac number, because 20042081 - 2¹⁸ = 19779937 is a prime.

It is a super-2 number, since 2×20042081² = 803370021621122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20042041) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10550 + ... + 12303.

It is an arithmetic number, because the mean of its divisors is an integer number (5016453).

Almost surely, 2^20042081 is an apocalyptic number.

It is an amenable number.

20042081 is a deficient number, since it is larger than the sum of its proper divisors (23731).

20042081 is an equidigital number, since it uses as much as digits as its factorization.

20042081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23730.

The product of its (nonzero) digits is 128, while the sum is 17.

The square root of 20042081 is about 4476.8382816448. The cubic root of 20042081 is about 271.6320039749.

Adding to 20042081 its reverse (18024002), we get a palindrome (38066083).

The spelling of 20042081 in words is "twenty million, forty-two thousand, eighty-one".