81550078 has 4 divisors (see below), whose sum is σ = 122325120. Its totient is φ = 40775038.

The previous prime is 81550069. The next prime is 81550087. The reversal of 81550078 is 87005518.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 87005518 = 2 ⋅43502759.

It is an interprime number because it is at equal distance from previous prime (81550069) and next prime (81550087).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20387518 + ... + 20387521.

It is an arithmetic number, because the mean of its divisors is an integer number (30581280).

Almost surely, 2^81550078 is an apocalyptic number.

81550078 is a deficient number, since it is larger than the sum of its proper divisors (40775042).

81550078 is a wasteful number, since it uses less digits than its factorization.

81550078 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40775041.

The product of its (nonzero) digits is 11200, while the sum is 34.

The square root of 81550078 is about 9030.5081806064. The cubic root of 81550078 is about 433.6521064033.

The spelling of 81550078 in words is "eighty-one million, five hundred fifty thousand, seventy-eight".