81518966 has 4 divisors (see below), whose sum is σ = 122278452. Its totient is φ = 40759482.

The previous prime is 81518963. The next prime is 81518977. The reversal of 81518966 is 66981518.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81518963) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20379740 + ... + 20379743.

It is an arithmetic number, because the mean of its divisors is an integer number (30569613).

Almost surely, 2^81518966 is an apocalyptic number.

81518966 is a deficient number, since it is larger than the sum of its proper divisors (40759486).

81518966 is a wasteful number, since it uses less digits than its factorization.

81518966 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40759485.

The product of its digits is 103680, while the sum is 44.

The square root of 81518966 is about 9028.7854111170. The cubic root of 81518966 is about 433.5969521522.

The spelling of 81518966 in words is "eighty-one million, five hundred eighteen thousand, nine hundred sixty-six".