81771516 has 36 divisors (see below), whose sum is σ = 217581000. Its totient is φ = 25822368.

The previous prime is 81771511. The next prime is 81771539. The reversal of 81771516 is 61517718.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81771511) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 59091 + ... + 60458.

Almost surely, 2^81771516 is an apocalyptic number.

It is an amenable number.

81771516 is an abundant number, since it is smaller than the sum of its proper divisors (135809484).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81771516 is a wasteful number, since it uses less digits than its factorization.

81771516 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 119578 (or 119573 counting only the distinct ones).

The product of its digits is 11760, while the sum is 36.

The square root of 81771516 is about 9042.7604192525. The cubic root of 81771516 is about 434.0442591855.

The spelling of 81771516 in words is "eighty-one million, seven hundred seventy-one thousand, five hundred sixteen".