81409117 has 2 divisors, whose sum is σ = 81409118. Its totient is φ = 81409116.

The previous prime is 81409063. The next prime is 81409187. The reversal of 81409117 is 71190418.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 48358116 + 33051001 = 6954^2 + 5749^2 .

It is a cyclic number.

It is not a de Polignac number, because 81409117 - 2⁷ = 81408989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81409187) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40704558 + 40704559.

It is an arithmetic number, because the mean of its divisors is an integer number (40704559).

Almost surely, 2^81409117 is an apocalyptic number.

It is an amenable number.

81409117 is a deficient number, since it is larger than the sum of its proper divisors (1).

81409117 is an equidigital number, since it uses as much as digits as its factorization.

81409117 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2016, while the sum is 31.

The square root of 81409117 is about 9022.7000947610. The cubic root of 81409117 is about 433.4021034183.

The spelling of 81409117 in words is "eighty-one million, four hundred nine thousand, one hundred seventeen".