81783766215 has 12 divisors (see below), whose sum is σ = 141758528184. Its totient is φ = 43618008624.

The previous prime is 81783766199. The next prime is 81783766283. The reversal of 81783766215 is 51266738718.

It is a happy number.

81783766215 is a `hidden beast` number, since 8 + 1 + 7 + 8 + 3 + 7 + 6 + 621 + 5 = 666.

It is not a de Polignac number, because 81783766215 - 2⁴ = 81783766199 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 908708469 + ... + 908708558.

It is an arithmetic number, because the mean of its divisors is an integer number (11813210682).

Almost surely, 2^81783766215 is an apocalyptic number.

81783766215 is a deficient number, since it is larger than the sum of its proper divisors (59974761969).

81783766215 is a wasteful number, since it uses less digits than its factorization.

81783766215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1817417038 (or 1817417035 counting only the distinct ones).

The product of its digits is 3386880, while the sum is 54.

The spelling of 81783766215 in words is "eighty-one billion, seven hundred eighty-three million, seven hundred sixty-six thousand, two hundred fifteen".