81581207 has 8 divisors (see below), whose sum is σ = 85255296. Its totient is φ = 77917752.

The previous prime is 81581197. The next prime is 81581233. The reversal of 81581207 is 70218518.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 81581207 - 2⁸ = 81580951 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81581107) 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, 15848 + ... + 20354.

It is an arithmetic number, because the mean of its divisors is an integer number (10656912).

Almost surely, 2^81581207 is an apocalyptic number.

81581207 is a deficient number, since it is larger than the sum of its proper divisors (3674089).

81581207 is a wasteful number, since it uses less digits than its factorization.

81581207 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5317.

The product of its (nonzero) digits is 4480, while the sum is 32.

The square root of 81581207 is about 9032.2315625763. The cubic root of 81581207 is about 433.7072767538.

The spelling of 81581207 in words is "eighty-one million, five hundred eighty-one thousand, two hundred seven".