81279009 has 12 divisors (see below), whose sum is σ = 134174976. Its totient is φ = 46445112.

The previous prime is 81279007. The next prime is 81279013. The reversal of 81279009 is 90097218.

It is a happy number.

It is not a de Polignac number, because 81279009 - 2¹ = 81279007 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81279007) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 645009 + ... + 645134.

It is an arithmetic number, because the mean of its divisors is an integer number (11181248).

Almost surely, 2^81279009 is an apocalyptic number.

It is an amenable number.

81279009 is a deficient number, since it is larger than the sum of its proper divisors (52895967).

81279009 is a wasteful number, since it uses less digits than its factorization.

81279009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1290156 (or 1290153 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 36.

The square root of 81279009 is about 9015.4871748564. The cubic root of 81279009 is about 433.1710926503.

The spelling of 81279009 in words is "eighty-one million, two hundred seventy-nine thousand, nine".