81121282515 has 640 divisors, whose sum is σ = 201705799680. Its totient is φ = 30233088000.

The previous prime is 81121282513. The next prime is 81121282531. The reversal of 81121282515 is 51528212118.

81121282515 is a `hidden beast` number, since 8 + 1 + 12 + 128 + 2 + 515 = 666.

It is not a de Polignac number, because 81121282515 - 2¹ = 81121282513 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81121282515.

It is not an unprimeable number, because it can be changed into a prime (81121282513) by changing a digit.

It is a polite number, since it can be written in 639 ways as a sum of consecutive naturals, for example, 803180965 + ... + 803181065.

It is an arithmetic number, because the mean of its divisors is an integer number (315165312).

Almost surely, 2^81121282515 is an apocalyptic number.

81121282515 is an abundant number, since it is smaller than the sum of its proper divisors (120584517165).

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

81121282515 is a wasteful number, since it uses less digits than its factorization.

81121282515 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 225 (or 216 counting only the distinct ones).

The product of its digits is 12800, while the sum is 36.

The spelling of 81121282515 in words is "eighty-one billion, one hundred twenty-one million, two hundred eighty-two thousand, five hundred fifteen".