21118297 has 4 divisors (see below), whose sum is σ = 21229056. Its totient is φ = 21007540.

The previous prime is 21118277. The next prime is 21118303. The reversal of 21118297 is 79281112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21118297 - 2¹⁵ = 21085529 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21118247) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 55093 + ... + 55474.

It is an arithmetic number, because the mean of its divisors is an integer number (5307264).

Almost surely, 2^21118297 is an apocalyptic number.

It is an amenable number.

21118297 is a deficient number, since it is larger than the sum of its proper divisors (110759).

21118297 is a wasteful number, since it uses less digits than its factorization.

21118297 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110758.

The product of its digits is 2016, while the sum is 31.

The square root of 21118297 is about 4595.4648295901. The cubic root of 21118297 is about 276.4094994232.

The spelling of 21118297 in words is "twenty-one million, one hundred eighteen thousand, two hundred ninety-seven".