81550517 has 8 divisors (see below), whose sum is σ = 85118040. Its totient is φ = 78058240.

The previous prime is 81550507. The next prime is 81550543. The reversal of 81550517 is 71505518.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 568516 + 80982001 = 754^2 + 8999^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81550517 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 (81550507) 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, 16592 + ... + 20937.

It is an arithmetic number, because the mean of its divisors is an integer number (10639755).

Almost surely, 2^81550517 is an apocalyptic number.

It is an amenable number.

81550517 is a deficient number, since it is larger than the sum of its proper divisors (3567523).

81550517 is a wasteful number, since it uses less digits than its factorization.

81550517 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37623.

The product of its (nonzero) digits is 7000, while the sum is 32.

The square root of 81550517 is about 9030.5324870685. The cubic root of 81550517 is about 433.6528845466.

The spelling of 81550517 in words is "eighty-one million, five hundred fifty thousand, five hundred seventeen".