20556240 has 80 divisors (see below), whose sum is σ = 64454208. Its totient is φ = 5419008.

The previous prime is 20556223. The next prime is 20556269. The reversal of 20556240 is 4265502.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 20556240.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 22839 + ... + 23721.

Almost surely, 2^20556240 is an apocalyptic number.

20556240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20556240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32227104).

20556240 is an abundant number, since it is smaller than the sum of its proper divisors (43897968).

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

20556240 is a wasteful number, since it uses less digits than its factorization.

20556240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 996 (or 990 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 24.

The square root of 20556240 is about 4533.8989843180. The cubic root of 20556240 is about 273.9352325294.

The spelling of 20556240 in words is "twenty million, five hundred fifty-six thousand, two hundred forty".