20495309 has 4 divisors (see below), whose sum is σ = 21156480. Its totient is φ = 19834140.

The previous prime is 20495303. The next prime is 20495317. The reversal of 20495309 is 90359402.

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 a de Polignac number, because none of the positive numbers 2^k-20495309 is a prime.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20495303) 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, 330539 + ... + 330600.

It is an arithmetic number, because the mean of its divisors is an integer number (5289120).

Almost surely, 2^20495309 is an apocalyptic number.

It is an amenable number.

20495309 is a deficient number, since it is larger than the sum of its proper divisors (661171).

20495309 is an equidigital number, since it uses as much as digits as its factorization.

20495309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 661170.

The product of its (nonzero) digits is 9720, while the sum is 32.

The square root of 20495309 is about 4527.1745051411. The cubic root of 20495309 is about 273.6643064206.

The spelling of 20495309 in words is "twenty million, four hundred ninety-five thousand, three hundred nine".