20864646 has 48 divisors (see below), whose sum is σ = 49690368. Its totient is φ = 6274800.

The previous prime is 20864617. The next prime is 20864647. The reversal of 20864646 is 64646802.

It is a happy number.

20864646 is a `hidden beast` number, since 2 + 0 + 8 + 6 + 4 + 646 = 666.

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 20864646.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20864647) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 32751 + ... + 33381.

It is an arithmetic number, because the mean of its divisors is an integer number (1035216).

Almost surely, 2^20864646 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20864646, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24845184).

20864646 is an abundant number, since it is smaller than the sum of its proper divisors (28825722).

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

20864646 is a wasteful number, since it uses less digits than its factorization.

20864646 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 817 (or 814 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 36.

The square root of 20864646 is about 4567.7834887394. The cubic root of 20864646 is about 275.2983912622.

The spelling of 20864646 in words is "twenty million, eight hundred sixty-four thousand, six hundred forty-six".