81278401 has 4 divisors (see below), whose sum is σ = 81871812. Its totient is φ = 80684992.

The previous prime is 81278383. The next prime is 81278423. The reversal of 81278401 is 10487218.

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

It can be written as a sum of positive squares in 2 ways, for example, as 15992001 + 65286400 = 3999^2 + 8080^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81278401 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81278101) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 296500 + ... + 296773.

It is an arithmetic number, because the mean of its divisors is an integer number (20467953).

Almost surely, 2^81278401 is an apocalyptic number.

It is an amenable number.

81278401 is a deficient number, since it is larger than the sum of its proper divisors (593411).

81278401 is a wasteful number, since it uses less digits than its factorization.

81278401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 593410.

The product of its (nonzero) digits is 3584, while the sum is 31.

The square root of 81278401 is about 9015.4534550404. The cubic root of 81278401 is about 433.1700125491.

The spelling of 81278401 in words is "eighty-one million, two hundred seventy-eight thousand, four hundred one".