81582551 has 2 divisors, whose sum is σ = 81582552. Its totient is φ = 81582550.

The previous prime is 81582499. The next prime is 81582577. The reversal of 81582551 is 15528518.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81582551 - 2¹⁰ = 81581527 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81585551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40791275 + 40791276.

It is an arithmetic number, because the mean of its divisors is an integer number (40791276).

Almost surely, 2^81582551 is an apocalyptic number.

81582551 is a deficient number, since it is larger than the sum of its proper divisors (1).

81582551 is an equidigital number, since it uses as much as digits as its factorization.

81582551 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 16000, while the sum is 35.

The square root of 81582551 is about 9032.3059624882. The cubic root of 81582551 is about 433.7096584273.

The spelling of 81582551 in words is "eighty-one million, five hundred eighty-two thousand, five hundred fifty-one".