20443781 has 2 divisors, whose sum is σ = 20443782. Its totient is φ = 20443780.

The previous prime is 20443771. The next prime is 20443783. The reversal of 20443781 is 18734402.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13468900 + 6974881 = 3670^2 + 2641^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20443781 is a prime.

It is a super-3 number, since 3×20443781³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

Together with 20443783, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20443783) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10221890 + 10221891.

It is an arithmetic number, because the mean of its divisors is an integer number (10221891).

Almost surely, 2^20443781 is an apocalyptic number.

It is an amenable number.

20443781 is a deficient number, since it is larger than the sum of its proper divisors (1).

20443781 is an equidigital number, since it uses as much as digits as its factorization.

20443781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5376, while the sum is 29.

The square root of 20443781 is about 4521.4799568283. The cubic root of 20443781 is about 273.4347708310.

The spelling of 20443781 in words is "twenty million, four hundred forty-three thousand, seven hundred eighty-one".