20043981 has 6 divisors (see below), whose sum is σ = 28952430. Its totient is φ = 13362648.

The previous prime is 20043967. The next prime is 20044009. The reversal of 20043981 is 18934002.

It can be written as a sum of positive squares in only one way, i.e., 18922500 + 1121481 = 4350^2 + 1059^2 .

It is not a de Polignac number, because 20043981 - 2⁷ = 20043853 is a prime.

It is a super-2 number, since 2×20043981² = 803522348656722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20043181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1113546 + ... + 1113563.

It is an arithmetic number, because the mean of its divisors is an integer number (4825405).

Almost surely, 2^20043981 is an apocalyptic number.

It is an amenable number.

20043981 is a deficient number, since it is larger than the sum of its proper divisors (8908449).

20043981 is a wasteful number, since it uses less digits than its factorization.

20043981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2227115 (or 2227112 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 20043981 is about 4477.0504799477. The cubic root of 20043981 is about 271.6405873234.

Adding to 20043981 its reverse (18934002), we get a palindrome (38977983).

The spelling of 20043981 in words is "twenty million, forty-three thousand, nine hundred eighty-one".