81920897 has 2 divisors, whose sum is σ = 81920898. Its totient is φ = 81920896.

The previous prime is 81920893. The next prime is 81920899. The reversal of 81920897 is 79802918.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 79637776 + 2283121 = 8924^2 + 1511^2 .

It is a cyclic number.

It is not a de Polignac number, because 81920897 - 2² = 81920893 is a prime.

It is a super-2 number, since 2×81920897² = 13422066730569218, which contains 22 as substring.

Together with 81920899, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81920893) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40960448 + 40960449.

It is an arithmetic number, because the mean of its divisors is an integer number (40960449).

Almost surely, 2^81920897 is an apocalyptic number.

It is an amenable number.

81920897 is a deficient number, since it is larger than the sum of its proper divisors (1).

81920897 is an equidigital number, since it uses as much as digits as its factorization.

81920897 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72576, while the sum is 44.

The square root of 81920897 is about 9051.0163517696. The cubic root of 81920897 is about 434.3084038269.

The spelling of 81920897 in words is "eighty-one million, nine hundred twenty thousand, eight hundred ninety-seven".