21004097 has 4 divisors (see below), whose sum is σ = 21038016. Its totient is φ = 20970180.

The previous prime is 21004073. The next prime is 21004099. The reversal of 21004097 is 79040012.

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 a de Polignac number, because none of the positive numbers 2^k-21004097 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21004099) 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, 16013 + ... + 17274.

It is an arithmetic number, because the mean of its divisors is an integer number (5259504).

Almost surely, 2^21004097 is an apocalyptic number.

It is an amenable number.

21004097 is a deficient number, since it is larger than the sum of its proper divisors (33919).

21004097 is an equidigital number, since it uses as much as digits as its factorization.

21004097 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33918.

The product of its (nonzero) digits is 504, while the sum is 23.

The square root of 21004097 is about 4583.0226925033. The cubic root of 21004097 is about 275.9103582371.

The spelling of 21004097 in words is "twenty-one million, four thousand, ninety-seven".