81517783 has 4 divisors (see below), whose sum is σ = 81630640. Its totient is φ = 81404928.

The previous prime is 81517757. The next prime is 81517789. The reversal of 81517783 is 38771518.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81517783 - 2¹³ = 81509591 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81517789) 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, 55338 + ... + 56791.

It is an arithmetic number, because the mean of its divisors is an integer number (20407660).

Almost surely, 2^81517783 is an apocalyptic number.

81517783 is a deficient number, since it is larger than the sum of its proper divisors (112857).

81517783 is a wasteful number, since it uses less digits than its factorization.

81517783 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 112856.

The product of its digits is 47040, while the sum is 40.

The square root of 81517783 is about 9028.7198981915. The cubic root of 81517783 is about 433.5948546948.

The spelling of 81517783 in words is "eighty-one million, five hundred seventeen thousand, seven hundred eighty-three".