20556220 has 24 divisors (see below), whose sum is σ = 43513344. Its totient is φ = 8156736.

The previous prime is 20556199. The next prime is 20556223. The reversal of 20556220 is 2265502.

It is a junction number, because it is equal to n+sod(n) for n = 20556191 and 20556200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20556223) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1507 + ... + 6586.

It is an arithmetic number, because the mean of its divisors is an integer number (1813056).

Almost surely, 2^20556220 is an apocalyptic number.

20556220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20556220 is an abundant number, since it is smaller than the sum of its proper divisors (22957124).

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

20556220 is a wasteful number, since it uses less digits than its factorization.

20556220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8229 (or 8227 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 22.

The square root of 20556220 is about 4533.8967787103. The cubic root of 20556220 is about 273.9351436884.

The spelling of 20556220 in words is "twenty million, five hundred fifty-six thousand, two hundred twenty".