81910078 has 4 divisors (see below), whose sum is σ = 122865120. Its totient is φ = 40955038.

The previous prime is 81910033. The next prime is 81910099. The reversal of 81910078 is 87001918.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20477518 + ... + 20477521.

It is an arithmetic number, because the mean of its divisors is an integer number (30716280).

Almost surely, 2^81910078 is an apocalyptic number.

81910078 is a deficient number, since it is larger than the sum of its proper divisors (40955042).

81910078 is a wasteful number, since it uses less digits than its factorization.

81910078 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40955041.

The product of its (nonzero) digits is 4032, while the sum is 34.

The square root of 81910078 is about 9050.4186643492. The cubic root of 81910078 is about 434.2892837991.

The spelling of 81910078 in words is "eighty-one million, nine hundred ten thousand, seventy-eight".