81585401 has 2 divisors, whose sum is σ = 81585402. Its totient is φ = 81585400.

The previous prime is 81585353. The next prime is 81585403. The reversal of 81585401 is 10458518.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 42510400 + 39075001 = 6520^2 + 6251^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81585401 is a prime.

Together with 81585403, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81585403) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40792700 + 40792701.

It is an arithmetic number, because the mean of its divisors is an integer number (40792701).

Almost surely, 2^81585401 is an apocalyptic number.

It is an amenable number.

81585401 is a deficient number, since it is larger than the sum of its proper divisors (1).

81585401 is an equidigital number, since it uses as much as digits as its factorization.

81585401 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6400, while the sum is 32.

The square root of 81585401 is about 9032.4637281309. The cubic root of 81585401 is about 433.7147087643.

The spelling of 81585401 in words is "eighty-one million, five hundred eighty-five thousand, four hundred one".