81432947 has 4 divisors (see below), whose sum is σ = 81500016. Its totient is φ = 81365880.

The previous prime is 81432889. The next prime is 81432959. The reversal of 81432947 is 74923418.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 74923418 = 2 ⋅37461709.

It is a cyclic number.

It is not a de Polignac number, because 81432947 - 2¹⁰ = 81431923 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81432947.

It is not an unprimeable number, because it can be changed into a prime (81437947) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 31679 + ... + 34152.

It is an arithmetic number, because the mean of its divisors is an integer number (20375004).

Almost surely, 2^81432947 is an apocalyptic number.

81432947 is a deficient number, since it is larger than the sum of its proper divisors (67069).

81432947 is a wasteful number, since it uses less digits than its factorization.

81432947 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67068.

The product of its digits is 48384, while the sum is 38.

The square root of 81432947 is about 9024.0205562709. The cubic root of 81432947 is about 433.4443876445. Note that the first 3 decimals are identical.

The spelling of 81432947 in words is "eighty-one million, four hundred thirty-two thousand, nine hundred forty-seven".