20720420 has 72 divisors (see below), whose sum is σ = 51567936. Its totient is φ = 6849216.

The previous prime is 20720417. The next prime is 20720423. The reversal of 20720420 is 2402702.

It is an interprime number because it is at equal distance from previous prime (20720417) and next prime (20720423).

It is not an unprimeable number, because it can be changed into a prime (20720423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 309227 + ... + 309293.

Almost surely, 2^20720420 is an apocalyptic number.

20720420 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 20720420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25783968).

20720420 is an abundant number, since it is smaller than the sum of its proper divisors (30847516).

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

20720420 is a wasteful number, since it uses less digits than its factorization.

20720420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 177 (or 128 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 17.

The square root of 20720420 is about 4551.9688048140. The cubic root of 20720420 is about 274.6625944610.

The spelling of 20720420 in words is "twenty million, seven hundred twenty thousand, four hundred twenty".