81978614 has 4 divisors (see below), whose sum is σ = 122967924. Its totient is φ = 40989306.

The previous prime is 81978613. The next prime is 81978619. The reversal of 81978614 is 41687918.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 41687918 = 2 ⋅20843959.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81978613) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20494652 + ... + 20494655.

It is an arithmetic number, because the mean of its divisors is an integer number (30741981).

Almost surely, 2^81978614 is an apocalyptic number.

81978614 is a deficient number, since it is larger than the sum of its proper divisors (40989310).

81978614 is a wasteful number, since it uses less digits than its factorization.

81978614 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40989309.

The product of its digits is 96768, while the sum is 44.

The square root of 81978614 is about 9054.2042168266. The cubic root of 81978614 is about 434.4103765608.

The spelling of 81978614 in words is "eighty-one million, nine hundred seventy-eight thousand, six hundred fourteen".