20665456 has 60 divisors (see below), whose sum is σ = 47737272. Its totient is φ = 8636544.

The previous prime is 20665451. The next prime is 20665459. The reversal of 20665456 is 65456602.

It is a super-2 number, since 2×20665456² = 854122143375872, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20665451) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 33406 + ... + 34018.

Almost surely, 2^20665456 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 20665456, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23868636).

20665456 is an abundant number, since it is smaller than the sum of its proper divisors (27071816).

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

20665456 is a wasteful number, since it uses less digits than its factorization.

20665456 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 678 (or 665 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 34.

The square root of 20665456 is about 4545.9274081314. The cubic root of 20665456 is about 274.4195182562.

The spelling of 20665456 in words is "twenty million, six hundred sixty-five thousand, four hundred fifty-six".