21008297 has 4 divisors (see below), whose sum is σ = 21686016. Its totient is φ = 20330580.

The previous prime is 21008293. The next prime is 21008329. The reversal of 21008297 is 79280012.

It is a happy number.

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 21008297 - 2² = 21008293 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21008291) 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 3 ways as a sum of consecutive naturals, for example, 338813 + ... + 338874.

It is an arithmetic number, because the mean of its divisors is an integer number (5421504).

Almost surely, 2^21008297 is an apocalyptic number.

It is an amenable number.

21008297 is a deficient number, since it is larger than the sum of its proper divisors (677719).

21008297 is an equidigital number, since it uses as much as digits as its factorization.

21008297 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 677718.

The product of its (nonzero) digits is 2016, while the sum is 29.

The square root of 21008297 is about 4583.4808824735. The cubic root of 21008297 is about 275.9287474474.

The spelling of 21008297 in words is "twenty-one million, eight thousand, two hundred ninety-seven".