20497209 has 8 divisors (see below), whose sum is σ = 28517952. Its totient is φ = 13070640.

The previous prime is 20497201. The next prime is 20497237. The reversal of 20497209 is 90279402.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20497209 - 2³ = 20497201 is a prime.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 20497209.

It is not an unprimeable number, because it can be changed into a prime (20497201) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 148462 + ... + 148599.

It is an arithmetic number, because the mean of its divisors is an integer number (3564744).

Almost surely, 2^20497209 is an apocalyptic number.

It is an amenable number.

20497209 is a deficient number, since it is larger than the sum of its proper divisors (8020743).

20497209 is a wasteful number, since it uses less digits than its factorization.

20497209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 297087.

The product of its (nonzero) digits is 9072, while the sum is 33.

The square root of 20497209 is about 4527.3843441882. The cubic root of 20497209 is about 273.6727627641.

It can be divided in two parts, 20497 and 209, that added together give a triangular number (20706 = T₂₀₃).

The spelling of 20497209 in words is "twenty million, four hundred ninety-seven thousand, two hundred nine".