81719205 has 16 divisors (see below), whose sum is σ = 130987584. Its totient is φ = 43504640.

The previous prime is 81719203. The next prime is 81719213. The reversal of 81719205 is 50291718.

It is not a de Polignac number, because 81719205 - 2¹ = 81719203 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81719203) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4165 + ... + 13445.

It is an arithmetic number, because the mean of its divisors is an integer number (8186724).

Almost surely, 2^81719205 is an apocalyptic number.

It is an amenable number.

81719205 is a deficient number, since it is larger than the sum of its proper divisors (49268379).

81719205 is a wasteful number, since it uses less digits than its factorization.

81719205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9876.

The product of its (nonzero) digits is 5040, while the sum is 33.

The square root of 81719205 is about 9039.8675322153. The cubic root of 81719205 is about 433.9516836215.

The spelling of 81719205 in words is "eighty-one million, seven hundred nineteen thousand, two hundred five".