81266551599 has 8 divisors (see below), whose sum is σ = 109314299952. Its totient is φ = 53698252160.

The previous prime is 81266551577. The next prime is 81266551627. The reversal of 81266551599 is 99515566218.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81266551599 - 2⁸ = 81266551343 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81266551999) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 119861832 + ... + 119862509.

It is an arithmetic number, because the mean of its divisors is an integer number (13664287494).

Almost surely, 2^81266551599 is an apocalyptic number.

81266551599 is a deficient number, since it is larger than the sum of its proper divisors (28047748353).

81266551599 is a wasteful number, since it uses less digits than its factorization.

81266551599 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 239724457.

The product of its digits is 5832000, while the sum is 57.

The spelling of 81266551599 in words is "eighty-one billion, two hundred sixty-six million, five hundred fifty-one thousand, five hundred ninety-nine".