85471781 has 2 divisors, whose sum is σ = 85471782. Its totient is φ = 85471780.

The previous prime is 85471777. The next prime is 85471783. The reversal of 85471781 is 18717458.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 74114881 + 11356900 = 8609^2 + 3370^2 .

It is a cyclic number.

It is not a de Polignac number, because 85471781 - 2² = 85471777 is a prime.

It is a super-2 number, since 2×85471781² = 14610850694623922, which contains 22 as substring.

Together with 85471783, 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 (85471783) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 42735890 + 42735891.

It is an arithmetic number, because the mean of its divisors is an integer number (42735891).

Almost surely, 2^85471781 is an apocalyptic number.

It is an amenable number.

85471781 is a deficient number, since it is larger than the sum of its proper divisors (1).

85471781 is an equidigital number, since it uses as much as digits as its factorization.

85471781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 62720, while the sum is 41.

The square root of 85471781 is about 9245.0949697664. The cubic root of 85471781 is about 440.4949337677.

The spelling of 85471781 in words is "eighty-five million, four hundred seventy-one thousand, seven hundred eighty-one".