81547431 has 8 divisors (see below), whose sum is σ = 124262784. Its totient is φ = 46598520.

The previous prime is 81547421. The next prime is 81547439. The reversal of 81547431 is 13474518.

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

It is not a de Polignac number, because 81547431 - 2¹¹ = 81545383 is a prime.

It is a super-2 number, since 2×81547431² = 13299967005399522, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81547392 and 81547401.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81547439) 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, 1941585 + ... + 1941626.

It is an arithmetic number, because the mean of its divisors is an integer number (15532848).

Almost surely, 2^81547431 is an apocalyptic number.

81547431 is a deficient number, since it is larger than the sum of its proper divisors (42715353).

81547431 is a wasteful number, since it uses less digits than its factorization.

81547431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3883221.

The product of its digits is 13440, while the sum is 33.

The square root of 81547431 is about 9030.3616206661. The cubic root of 81547431 is about 433.6474144415.

The spelling of 81547431 in words is "eighty-one million, five hundred forty-seven thousand, four hundred thirty-one".