43478521781 has 2 divisors, whose sum is σ = 43478521782. Its totient is φ = 43478521780.

The previous prime is 43478521747. The next prime is 43478521783. The reversal of 43478521781 is 18712587434.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 34444019281 + 9034502500 = 185591^2 + 95050^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-43478521781 is a prime.

It is a super-2 number, since 2×43478521781² (a number of 22 digits) contains 22 as substring.

Together with 43478521783, 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 (43478521783) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21739260890 + 21739260891.

It is an arithmetic number, because the mean of its divisors is an integer number (21739260891).

Almost surely, 2^43478521781 is an apocalyptic number.

It is an amenable number.

43478521781 is a deficient number, since it is larger than the sum of its proper divisors (1).

43478521781 is an equidigital number, since it uses as much as digits as its factorization.

43478521781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1505280, while the sum is 50.

The spelling of 43478521781 in words is "forty-three billion, four hundred seventy-eight million, five hundred twenty-one thousand, seven hundred eighty-one".