81543651 has 8 divisors (see below), whose sum is σ = 124257024. Its totient is φ = 46596360.

The previous prime is 81543647. The next prime is 81543659. The reversal of 81543651 is 15634518.

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

It is not a de Polignac number, because 81543651 - 2² = 81543647 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81543659) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1941495 + ... + 1941536.

It is an arithmetic number, because the mean of its divisors is an integer number (15532128).

Almost surely, 2^81543651 is an apocalyptic number.

81543651 is a deficient number, since it is larger than the sum of its proper divisors (42713373).

81543651 is a wasteful number, since it uses less digits than its factorization.

81543651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3883041.

The product of its digits is 14400, while the sum is 33.

The square root of 81543651 is about 9030.1523242966. The cubic root of 81543651 is about 433.6407139952.

The spelling of 81543651 in words is "eighty-one million, five hundred forty-three thousand, six hundred fifty-one".