20423440 has 40 divisors (see below), whose sum is σ = 48300480. Its totient is φ = 8029056.

The previous prime is 20423407. The next prime is 20423441. The reversal of 20423440 is 4432402.

It is a tau number, because it is divible by the number of its divisors (40).

It is not an unprimeable number, because it can be changed into a prime (20423441) 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 7 ways as a sum of consecutive naturals, for example, 2557 + ... + 6883.

It is an arithmetic number, because the mean of its divisors is an integer number (1207512).

Almost surely, 2^20423440 is an apocalyptic number.

20423440 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 20423440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24150240).

20423440 is an abundant number, since it is smaller than the sum of its proper divisors (27877040).

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

20423440 is a wasteful number, since it uses less digits than its factorization.

20423440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4399 (or 4393 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 19.

The square root of 20423440 is about 4519.2300229132. The cubic root of 20423440 is about 273.3440540444.

Adding to 20423440 its reverse (4432402), we get a palindrome (24855842).

The spelling of 20423440 in words is "twenty million, four hundred twenty-three thousand, four hundred forty".