21197097 has 6 divisors (see below), whose sum is σ = 30618042. Its totient is φ = 14131392.

The previous prime is 21197093. The next prime is 21197117. The reversal of 21197097 is 79079112.

It can be written as a sum of positive squares in only one way, i.e., 21013056 + 184041 = 4584^2 + 429^2 .

It is not a de Polignac number, because 21197097 - 2² = 21197093 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21197093) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1177608 + ... + 1177625.

It is an arithmetic number, because the mean of its divisors is an integer number (5103007).

Almost surely, 2^21197097 is an apocalyptic number.

It is an amenable number.

21197097 is a deficient number, since it is larger than the sum of its proper divisors (9420945).

21197097 is a wasteful number, since it uses less digits than its factorization.

21197097 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2355239 (or 2355236 counting only the distinct ones).

The product of its (nonzero) digits is 7938, while the sum is 36.

The square root of 21197097 is about 4604.0305168407. The cubic root of 21197097 is about 276.7528672867.

It can be divided in two parts, 2119 and 7097, that added together give a square (9216 = 96²).

The spelling of 21197097 in words is "twenty-one million, one hundred ninety-seven thousand, ninety-seven".