20971609 has 8 divisors (see below), whose sum is σ = 21450240. Its totient is φ = 20497200.

The previous prime is 20971583. The next prime is 20971619. The reversal of 20971609 is 90617902.

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

It is a cyclic number.

It is not a de Polignac number, because 20971609 - 2¹³ = 20963417 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20971619) 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, 10339 + ... + 12199.

It is an arithmetic number, because the mean of its divisors is an integer number (2681280).

Almost surely, 2^20971609 is an apocalyptic number.

It is an amenable number.

20971609 is a deficient number, since it is larger than the sum of its proper divisors (478631).

20971609 is a wasteful number, since it uses less digits than its factorization.

20971609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2111.

The product of its (nonzero) digits is 6804, while the sum is 34.

The square root of 20971609 is about 4579.4769351969. The cubic root of 20971609 is about 275.7680304291.

The spelling of 20971609 in words is "twenty million, nine hundred seventy-one thousand, six hundred nine".