20428440 has 128 divisors (see below), whose sum is σ = 65007360. Its totient is φ = 5128704.

The previous prime is 20428433. The next prime is 20428459. The reversal of 20428440 is 4482402.

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 20428440.

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, 190867 + ... + 190973.

It is an arithmetic number, because the mean of its divisors is an integer number (507870).

Almost surely, 2^20428440 is an apocalyptic number.

20428440 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 20428440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32503680).

20428440 is an abundant number, since it is smaller than the sum of its proper divisors (44578920).

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

20428440 is a wasteful number, since it uses less digits than its factorization.

20428440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 201 (or 197 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 24.

The square root of 20428440 is about 4519.7831806404. The cubic root of 20428440 is about 273.3663586244.

The spelling of 20428440 in words is "twenty million, four hundred twenty-eight thousand, four hundred forty".