81678615 has 16 divisors (see below), whose sum is σ = 130799616. Its totient is φ = 43524000.

The previous prime is 81678607. The next prime is 81678637. The reversal of 81678615 is 51687618.

It is not a de Polignac number, because 81678615 - 2³ = 81678607 is a prime.

It is a super-2 number, since 2×81678615² = 13342792296636450, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27870 + ... + 30660.

It is an arithmetic number, because the mean of its divisors is an integer number (8174976).

Almost surely, 2^81678615 is an apocalyptic number.

81678615 is a deficient number, since it is larger than the sum of its proper divisors (49121001).

81678615 is a wasteful number, since it uses less digits than its factorization.

81678615 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4750.

The product of its digits is 80640, while the sum is 42.

The square root of 81678615 is about 9037.6221983440. The cubic root of 81678615 is about 433.8798236633.

The spelling of 81678615 in words is "eighty-one million, six hundred seventy-eight thousand, six hundred fifteen".