81279985 has 8 divisors (see below), whose sum is σ = 100682496. Its totient is φ = 62926320.

The previous prime is 81279983. The next prime is 81280037. The reversal of 81279985 is 58997218.

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

It is not a de Polignac number, because 81279985 - 2¹ = 81279983 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81279983) 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, 262039 + ... + 262348.

It is an arithmetic number, because the mean of its divisors is an integer number (12585312).

Almost surely, 2^81279985 is an apocalyptic number.

It is an amenable number.

81279985 is a deficient number, since it is larger than the sum of its proper divisors (19402511).

81279985 is a wasteful number, since it uses less digits than its factorization.

81279985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 524423.

The product of its digits is 362880, while the sum is 49.

The square root of 81279985 is about 9015.5413037709. The cubic root of 81279985 is about 433.1728264858.

The spelling of 81279985 in words is "eighty-one million, two hundred seventy-nine thousand, nine hundred eighty-five".