20897009 has 4 divisors (see below), whose sum is σ = 23882304. Its totient is φ = 17911716.

The previous prime is 20896991. The next prime is 20897027. The reversal of 20897009 is 90079802.

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 an interprime number because it is at equal distance from previous prime (20896991) and next prime (20897027).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20897009 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 20897009.

It is not an unprimeable number, because it can be changed into a prime (20897039) 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, 1492637 + ... + 1492650.

It is an arithmetic number, because the mean of its divisors is an integer number (5970576).

Almost surely, 2^20897009 is an apocalyptic number.

It is an amenable number.

20897009 is a deficient number, since it is larger than the sum of its proper divisors (2985295).

20897009 is an equidigital number, since it uses as much as digits as its factorization.

20897009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2985294.

The product of its (nonzero) digits is 9072, while the sum is 35.

The square root of 20897009 is about 4571.3246439079. The cubic root of 20897009 is about 275.4406555071.

The spelling of 20897009 in words is "twenty million, eight hundred ninety-seven thousand, nine".