20809472 has 36 divisors (see below), whose sum is σ = 42985320. Its totient is φ = 10042368.

The previous prime is 20809471. The next prime is 20809487. The reversal of 20809472 is 27490802.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20809471) 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, 6023 + ... + 8825.

Almost surely, 2^20809472 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20809472, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21492660).

20809472 is an abundant number, since it is smaller than the sum of its proper divisors (22175848).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20809472 is an equidigital number, since it uses as much as digits as its factorization.

20809472 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2848 (or 2834 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 32.

The square root of 20809472 is about 4561.7400188963. The cubic root of 20809472 is about 275.0555127601.

The spelling of 20809472 in words is "twenty million, eight hundred nine thousand, four hundred seventy-two".