81555193 has 4 divisors (see below), whose sum is σ = 81635328. Its totient is φ = 81475060.

The previous prime is 81555179. The next prime is 81555197. The reversal of 81555193 is 39155518.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 39155518 = 2 ⋅19577759.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81555193 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81555197) by changing a digit.

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 in 3 ways as a sum of consecutive naturals, for example, 38521 + ... + 40582.

It is an arithmetic number, because the mean of its divisors is an integer number (20408832).

Almost surely, 2^81555193 is an apocalyptic number.

It is an amenable number.

81555193 is a deficient number, since it is larger than the sum of its proper divisors (80135).

81555193 is a wasteful number, since it uses less digits than its factorization.

81555193 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80134.

The product of its digits is 27000, while the sum is 37.

The square root of 81555193 is about 9030.7913828191. The cubic root of 81555193 is about 433.6611727513.

The spelling of 81555193 in words is "eighty-one million, five hundred fifty-five thousand, one hundred ninety-three".