81278555 has 8 divisors (see below), whose sum is σ = 97954272. Its totient is φ = 64742848.

The previous prime is 81278551. The next prime is 81278579. The reversal of 81278555 is 55587218.

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 81278555 - 2² = 81278551 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81278551) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 33719 + ... + 36048.

It is an arithmetic number, because the mean of its divisors is an integer number (12244284).

Almost surely, 2^81278555 is an apocalyptic number.

81278555 is a deficient number, since it is larger than the sum of its proper divisors (16675717).

81278555 is a wasteful number, since it uses less digits than its factorization.

81278555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70005.

The product of its digits is 112000, while the sum is 41.

The square root of 81278555 is about 9015.4619959268. The cubic root of 81278555 is about 433.1702861279.

The spelling of 81278555 in words is "eighty-one million, two hundred seventy-eight thousand, five hundred fifty-five".