81078401 has 2 divisors, whose sum is σ = 81078402. Its totient is φ = 81078400.

The previous prime is 81078391. The next prime is 81078409. The reversal of 81078401 is 10487018.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 77018176 + 4060225 = 8776^2 + 2015^2 .

It is a cyclic number.

It is not a de Polignac number, because 81078401 - 2¹⁴ = 81062017 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (81078409) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40539200 + 40539201.

It is an arithmetic number, because the mean of its divisors is an integer number (40539201).

Almost surely, 2^81078401 is an apocalyptic number.

It is an amenable number.

81078401 is a deficient number, since it is larger than the sum of its proper divisors (1).

81078401 is an equidigital number, since it uses as much as digits as its factorization.

81078401 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1792, while the sum is 29.

The square root of 81078401 is about 9004.3545576571. The cubic root of 81078401 is about 432.8144233716.

The spelling of 81078401 in words is "eighty-one million, seventy-eight thousand, four hundred one".