81672009 has 4 divisors (see below), whose sum is σ = 108896016. Its totient is φ = 54448004.

The previous prime is 81671977. The next prime is 81672037. The reversal of 81672009 is 90027618.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81672009 - 2⁵ = 81671977 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81632009) 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, 13611999 + ... + 13612004.

It is an arithmetic number, because the mean of its divisors is an integer number (27224004).

Almost surely, 2^81672009 is an apocalyptic number.

It is an amenable number.

81672009 is a deficient number, since it is larger than the sum of its proper divisors (27224007).

81672009 is a wasteful number, since it uses less digits than its factorization.

81672009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27224006.

The product of its (nonzero) digits is 6048, while the sum is 33.

The square root of 81672009 is about 9037.2567187172. The cubic root of 81672009 is about 433.8681262425.

The spelling of 81672009 in words is "eighty-one million, six hundred seventy-two thousand, nine".