20420556 has 48 divisors (see below), whose sum is σ = 51631104. Its totient is φ = 6244416.

The previous prime is 20420531. The next prime is 20420557. The reversal of 20420556 is 65502402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20420557) 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, 34495 + ... + 35081.

It is an arithmetic number, because the mean of its divisors is an integer number (1075648).

Almost surely, 2^20420556 is an apocalyptic number.

20420556 is a gapful number since it is divisible by the number (26) 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 20420556, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25815552).

20420556 is an abundant number, since it is smaller than the sum of its proper divisors (31210548).

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

20420556 is a wasteful number, since it uses less digits than its factorization.

20420556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 830 (or 828 counting only the distinct ones).

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

The square root of 20420556 is about 4518.9109307443. The cubic root of 20420556 is about 273.3311871072.

Adding to 20420556 its reverse (65502402), we get a palindrome (85922958).

The spelling of 20420556 in words is "twenty million, four hundred twenty thousand, five hundred fifty-six".