20490581 has 4 divisors (see below), whose sum is σ = 20566464. Its totient is φ = 20414700.

The previous prime is 20490557. The next prime is 20490599. The reversal of 20490581 is 18509402.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20490581 - 2⁶ = 20490517 is a prime.

It is a super-2 number, since 2×20490581² = 839727819435122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20490551) 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, 37535 + ... + 38076.

It is an arithmetic number, because the mean of its divisors is an integer number (5141616).

Almost surely, 2^20490581 is an apocalyptic number.

It is an amenable number.

20490581 is a deficient number, since it is larger than the sum of its proper divisors (75883).

20490581 is an equidigital number, since it uses as much as digits as its factorization.

20490581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75882.

The product of its (nonzero) digits is 2880, while the sum is 29.

The square root of 20490581 is about 4526.6522950189. The cubic root of 20490581 is about 273.6432612090.

Adding to 20490581 its reverse (18509402), we get a palindrome (38999983).

The spelling of 20490581 in words is "twenty million, four hundred ninety thousand, five hundred eighty-one".