81658397 has 2 divisors, whose sum is σ = 81658398. Its totient is φ = 81658396.

The previous prime is 81658391. The next prime is 81658417. The reversal of 81658397 is 79385618.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 80532676 + 1125721 = 8974^2 + 1061^2 .

It is a cyclic number.

It is not a de Polignac number, because 81658397 - 2⁸ = 81658141 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81658391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40829198 + 40829199.

It is an arithmetic number, because the mean of its divisors is an integer number (40829199).

Almost surely, 2^81658397 is an apocalyptic number.

It is an amenable number.

81658397 is a deficient number, since it is larger than the sum of its proper divisors (1).

81658397 is an equidigital number, since it uses as much as digits as its factorization.

81658397 is an evil number, because the sum of its binary digits is even.

The product of its digits is 362880, while the sum is 47.

The square root of 81658397 is about 9036.5035826917. The cubic root of 81658397 is about 433.8440211212.

The spelling of 81658397 in words is "eighty-one million, six hundred fifty-eight thousand, three hundred ninety-seven".