20642256 has 80 divisors (see below), whose sum is σ = 60174720. Its totient is φ = 6773760.

The previous prime is 20642239. The next prime is 20642257. The reversal of 20642256 is 65224602.

It is a super-3 number, since 3×20642256³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20642257) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 30336 + ... + 31008.

It is an arithmetic number, because the mean of its divisors is an integer number (752184).

Almost surely, 2^20642256 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 20642256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30087360).

20642256 is an abundant number, since it is smaller than the sum of its proper divisors (39532464).

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

20642256 is a wasteful number, since it uses less digits than its factorization.

20642256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 761 (or 749 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 27.

The square root of 20642256 is about 4543.3749570116. The cubic root of 20642256 is about 274.3167877742.

Adding to 20642256 its reverse (65224602), we get a palindrome (85866858).

The spelling of 20642256 in words is "twenty million, six hundred forty-two thousand, two hundred fifty-six".