97857821 has 2 divisors, whose sum is σ = 97857822. Its totient is φ = 97857820.

The previous prime is 97857811. The next prime is 97857827. The reversal of 97857821 is 12875879.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 81252196 + 16605625 = 9014^2 + 4075^2 .

It is an emirp because it is prime and its reverse (12875879) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 97857821 - 2⁶ = 97857757 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (97857827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 48928910 + 48928911.

It is an arithmetic number, because the mean of its divisors is an integer number (48928911).

Almost surely, 2^97857821 is an apocalyptic number.

It is an amenable number.

97857821 is a deficient number, since it is larger than the sum of its proper divisors (1).

97857821 is an equidigital number, since it uses as much as digits as its factorization.

97857821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 282240, while the sum is 47.

The square root of 97857821 is about 9892.3112061843. The cubic root of 97857821 is about 460.8205596542.

The spelling of 97857821 in words is "ninety-seven million, eight hundred fifty-seven thousand, eight hundred twenty-one".