81439571 has 16 divisors (see below), whose sum is σ = 88851168. Its totient is φ = 74342400.

The previous prime is 81439559. The next prime is 81439583. The reversal of 81439571 is 17593418.

It is an interprime number because it is at equal distance from previous prime (81439559) and next prime (81439583).

It is a cyclic number.

It is not a de Polignac number, because 81439571 - 2⁶ = 81439507 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81439541) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 230531 + ... + 230883.

It is an arithmetic number, because the mean of its divisors is an integer number (5553198).

Almost surely, 2^81439571 is an apocalyptic number.

81439571 is a deficient number, since it is larger than the sum of its proper divisors (7411597).

81439571 is a wasteful number, since it uses less digits than its factorization.

81439571 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 742.

The product of its digits is 30240, while the sum is 38.

The square root of 81439571 is about 9024.3875692481. The cubic root of 81439571 is about 433.4561398811.

The spelling of 81439571 in words is "eighty-one million, four hundred thirty-nine thousand, five hundred seventy-one".