20445140 has 48 divisors (see below), whose sum is σ = 45601920. Its totient is φ = 7678080.

The previous prime is 20445109. The next prime is 20445143. The reversal of 20445140 is 4154402.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20445143) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 65585 + ... + 65895.

It is an arithmetic number, because the mean of its divisors is an integer number (950040).

Almost surely, 2^20445140 is an apocalyptic number.

20445140 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 20445140, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22800960).

20445140 is an abundant number, since it is smaller than the sum of its proper divisors (25156780).

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

20445140 is a wasteful number, since it uses less digits than its factorization.

20445140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 512 (or 510 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 20.

The square root of 20445140 is about 4521.6302369831. The cubic root of 20445140 is about 273.4408295540.

Adding to 20445140 its reverse (4154402), we get a palindrome (24599542).

The spelling of 20445140 in words is "twenty million, four hundred forty-five thousand, one hundred forty".