81123615 has 24 divisors (see below), whose sum is σ = 141343488. Its totient is φ = 43041600.

The previous prime is 81123611. The next prime is 81123629. The reversal of 81123615 is 51632118.

It is not a de Polignac number, because 81123615 - 2² = 81123611 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81123611) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4290 + ... + 13440.

It is an arithmetic number, because the mean of its divisors is an integer number (5889312).

Almost surely, 2^81123615 is an apocalyptic number.

81123615 is a deficient number, since it is larger than the sum of its proper divisors (60219873).

81123615 is a wasteful number, since it uses less digits than its factorization.

81123615 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9359 (or 9356 counting only the distinct ones).

The product of its digits is 1440, while the sum is 27.

The square root of 81123615 is about 9006.8648818554. The cubic root of 81123615 is about 432.8948625291.

The spelling of 81123615 in words is "eighty-one million, one hundred twenty-three thousand, six hundred fifteen".