20289720 has 128 divisors (see below), whose sum is σ = 69984000. Its totient is φ = 4654080.

The previous prime is 20289713. The next prime is 20289733. The reversal of 20289720 is 2798202.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 24676 + ... + 25484.

It is an arithmetic number, because the mean of its divisors is an integer number (546750).

Almost surely, 2^20289720 is an apocalyptic number.

20289720 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 20289720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34992000).

20289720 is an abundant number, since it is smaller than the sum of its proper divisors (49694280).

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

20289720 is a wasteful number, since it uses less digits than its factorization.

20289720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 853 (or 849 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 30.

The square root of 20289720 is about 4504.4111712853. The cubic root of 20289720 is about 272.7461849511.

The spelling of 20289720 in words is "twenty million, two hundred eighty-nine thousand, seven hundred twenty".