21109297 has 6 divisors (see below), whose sum is σ = 23202914. Its totient is φ = 19190160.

The previous prime is 21109273. The next prime is 21109313. The reversal of 21109297 is 79290112.

It can be written as a sum of positive squares in only one way, i.e., 13905441 + 7203856 = 3729^2 + 2684^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21109297 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21109217) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 87108 + ... + 87349.

Almost surely, 2^21109297 is an apocalyptic number.

It is an amenable number.

21109297 is a deficient number, since it is larger than the sum of its proper divisors (2093617).

21109297 is a wasteful number, since it uses less digits than its factorization.

21109297 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 174479 (or 174468 counting only the distinct ones).

The product of its (nonzero) digits is 2268, while the sum is 31.

The square root of 21109297 is about 4594.4854989433. The cubic root of 21109297 is about 276.3702279648.

The spelling of 21109297 in words is "twenty-one million, one hundred nine thousand, two hundred ninety-seven".