81447999 has 8 divisors (see below), whose sum is σ = 108687360. Its totient is φ = 54253656.

The previous prime is 81447997. The next prime is 81448001. The reversal of 81447999 is 99974418.

It is an interprime number because it is at equal distance from previous prime (81447997) and next prime (81448001).

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

It is not a de Polignac number, because 81447999 - 2¹ = 81447997 is a prime.

It is a super-2 number, since 2×81447999² = 13267553082208002, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81447997) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6777 + ... + 14450.

It is an arithmetic number, because the mean of its divisors is an integer number (13585920).

Almost surely, 2^81447999 is an apocalyptic number.

81447999 is a deficient number, since it is larger than the sum of its proper divisors (27239361).

81447999 is a wasteful number, since it uses less digits than its factorization.

81447999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22509.

The product of its digits is 653184, while the sum is 51.

The square root of 81447999 is about 9024.8545140628. The cubic root of 81447999 is about 433.4710918358.

The spelling of 81447999 in words is "eighty-one million, four hundred forty-seven thousand, nine hundred ninety-nine".