21364909 has 4 divisors (see below), whose sum is σ = 22101660. Its totient is φ = 20628160.

The previous prime is 21364897. The next prime is 21364919. The reversal of 21364909 is 90946312.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 11410884 + 9954025 = 3378^2 + 3155^2 .

It is a cyclic number.

It is not a de Polignac number, because 21364909 - 2⁵ = 21364877 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21364919) 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, 368332 + ... + 368389.

It is an arithmetic number, because the mean of its divisors is an integer number (5525415).

Almost surely, 2^21364909 is an apocalyptic number.

21364909 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

21364909 is a deficient number, since it is larger than the sum of its proper divisors (736751).

21364909 is an equidigital number, since it uses as much as digits as its factorization.

21364909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 736750.

The product of its (nonzero) digits is 11664, while the sum is 34.

The square root of 21364909 is about 4622.2190558216. The cubic root of 21364909 is about 277.4812756892.

The spelling of 21364909 in words is "twenty-one million, three hundred sixty-four thousand, nine hundred nine".