81812211515 has 8 divisors (see below), whose sum is σ = 98177802720. Its totient is φ = 65447669952.

The previous prime is 81812211347. The next prime is 81812211521. The reversal of 81812211515 is 51511221818.

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

It is a cyclic number.

It is not a de Polignac number, because 81812211515 - 2¹⁴ = 81812195131 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 79319 + ... + 412208.

It is an arithmetic number, because the mean of its divisors is an integer number (12272225340).

Almost surely, 2^81812211515 is an apocalyptic number.

81812211515 is a deficient number, since it is larger than the sum of its proper divisors (16365591205).

81812211515 is a wasteful number, since it uses less digits than its factorization.

81812211515 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 524821.

The product of its digits is 6400, while the sum is 35.

The spelling of 81812211515 in words is "eighty-one billion, eight hundred twelve million, two hundred eleven thousand, five hundred fifteen".