20490817 has 4 divisors (see below), whose sum is σ = 20504260. Its totient is φ = 20477376.

The previous prime is 20490803. The next prime is 20490823. The reversal of 20490817 is 71809402.

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 11029041 + 9461776 = 3321^2 + 3076^2 .

It is a cyclic number.

It is not a de Polignac number, because 20490817 - 2⁷ = 20490689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20490017) 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, 4092 + ... + 7597.

It is an arithmetic number, because the mean of its divisors is an integer number (5126065).

Almost surely, 2^20490817 is an apocalyptic number.

It is an amenable number.

20490817 is a deficient number, since it is larger than the sum of its proper divisors (13443).

20490817 is a wasteful number, since it uses less digits than its factorization.

20490817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13442.

The product of its (nonzero) digits is 4032, while the sum is 31.

The square root of 20490817 is about 4526.6783627733. The cubic root of 20490817 is about 273.6443117658.

The spelling of 20490817 in words is "twenty million, four hundred ninety thousand, eight hundred seventeen".