81651585 has 8 divisors (see below), whose sum is σ = 130642560. Its totient is φ = 43547504.

The previous prime is 81651571. The next prime is 81651599. The reversal of 81651585 is 58515618.

It is an interprime number because it is at equal distance from previous prime (81651571) and next prime (81651599).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81651585 - 2¹⁰ = 81650561 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2721705 + ... + 2721734.

It is an arithmetic number, because the mean of its divisors is an integer number (16330320).

Almost surely, 2^81651585 is an apocalyptic number.

It is an amenable number.

81651585 is a deficient number, since it is larger than the sum of its proper divisors (48990975).

81651585 is a wasteful number, since it uses less digits than its factorization.

81651585 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5443447.

The product of its digits is 48000, while the sum is 39.

The square root of 81651585 is about 9036.1266591389. The cubic root of 81651585 is about 433.8319569295.

The spelling of 81651585 in words is "eighty-one million, six hundred fifty-one thousand, five hundred eighty-five".