97917821 has 2 divisors, whose sum is σ = 97917822. Its totient is φ = 97917820.

The previous prime is 97917817. The next prime is 97917823. The reversal of 97917821 is 12871979.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 88548100 + 9369721 = 9410^2 + 3061^2 .

It is a cyclic number.

It is not a de Polignac number, because 97917821 - 2² = 97917817 is a prime.

Together with 97917823, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (97917823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 48958910 + 48958911.

It is an arithmetic number, because the mean of its divisors is an integer number (48958911).

Almost surely, 2^97917821 is an apocalyptic number.

It is an amenable number.

97917821 is a deficient number, since it is larger than the sum of its proper divisors (1).

97917821 is an equidigital number, since it uses as much as digits as its factorization.

97917821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 63504, while the sum is 44.

The square root of 97917821 is about 9895.3433998017. The cubic root of 97917821 is about 460.9147220635.

The spelling of 97917821 in words is "ninety-seven million, nine hundred seventeen thousand, eight hundred twenty-one".