20290681 has 4 divisors (see below), whose sum is σ = 20325492. Its totient is φ = 20255872.

The previous prime is 20290661. The next prime is 20290693. The reversal of 20290681 is 18609202.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 16646400 + 3644281 = 4080^2 + 1909^2 .

It is a cyclic number.

It is not a de Polignac number, because 20290681 - 2⁵ = 20290649 is a prime.

It is a super-2 number, since 2×20290681² = 823423470887522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20290661) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16516 + ... + 17701.

It is an arithmetic number, because the mean of its divisors is an integer number (5081373).

Almost surely, 2^20290681 is an apocalyptic number.

It is an amenable number.

20290681 is a deficient number, since it is larger than the sum of its proper divisors (34811).

20290681 is an equidigital number, since it uses as much as digits as its factorization.

20290681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34810.

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 20290681 is about 4504.5178432325. The cubic root of 20290681 is about 272.7504909896.

Adding to 20290681 its reverse (18609202), we get a palindrome (38899883).

The spelling of 20290681 in words is "twenty million, two hundred ninety thousand, six hundred eighty-one".