21496209 has 16 divisors (see below), whose sum is σ = 32977920. Its totient is φ = 12200400.

The previous prime is 21496199. The next prime is 21496231. The reversal of 21496209 is 90269412.

It is a de Polignac number, because none of the positive numbers 2^k-21496209 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21496209.

It is not an unprimeable number, because it can be changed into a prime (21496309) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 219 + ... + 6560.

It is an arithmetic number, because the mean of its divisors is an integer number (2061120).

Almost surely, 2^21496209 is an apocalyptic number.

It is an amenable number.

21496209 is a deficient number, since it is larger than the sum of its proper divisors (11481711).

21496209 is a wasteful number, since it uses less digits than its factorization.

21496209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6940.

The product of its (nonzero) digits is 7776, while the sum is 33.

The square root of 21496209 is about 4636.4004356828. The cubic root of 21496209 is about 278.0485440477.

The spelling of 21496209 in words is "twenty-one million, four hundred ninety-six thousand, two hundred nine".