20391444 has 18 divisors (see below), whose sum is σ = 51545130. Its totient is φ = 6797136.

The previous prime is 20391443. The next prime is 20391451. The reversal of 20391444 is 44419302.

It can be written as a sum of positive squares in only one way, i.e., 18922500 + 1468944 = 4350^2 + 1212^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20391443) 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 5 ways as a sum of consecutive naturals, for example, 283179 + ... + 283250.

Almost surely, 2^20391444 is an apocalyptic number.

It is an amenable number.

20391444 is an abundant number, since it is smaller than the sum of its proper divisors (31153686).

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

20391444 is a wasteful number, since it uses less digits than its factorization.

20391444 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 566439 (or 566434 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

The square root of 20391444 is about 4515.6886518005. The cubic root of 20391444 is about 273.2012363222.

The spelling of 20391444 in words is "twenty million, three hundred ninety-one thousand, four hundred forty-four".