21208097 has 2 divisors, whose sum is σ = 21208098. Its totient is φ = 21208096.

The previous prime is 21208091. The next prime is 21208127. The reversal of 21208097 is 79080212.

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., 19088161 + 2119936 = 4369^2 + 1456^2 .

It is a cyclic number.

It is not a de Polignac number, because 21208097 - 2⁸ = 21207841 is a prime.

It is a super-2 number, since 2×21208097² = 899566756722818, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21208091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10604048 + 10604049.

It is an arithmetic number, because the mean of its divisors is an integer number (10604049).

Almost surely, 2^21208097 is an apocalyptic number.

It is an amenable number.

21208097 is a deficient number, since it is larger than the sum of its proper divisors (1).

21208097 is an equidigital number, since it uses as much as digits as its factorization.

21208097 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 29.

The square root of 21208097 is about 4605.2249673604. The cubic root of 21208097 is about 276.8007316254.

The spelling of 21208097 in words is "twenty-one million, two hundred eight thousand, ninety-seven".