21422409 has 4 divisors (see below), whose sum is σ = 28563216. Its totient is φ = 14281604.

The previous prime is 21422399. The next prime is 21422411. The reversal of 21422409 is 90422412.

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 21422409 - 2¹⁶ = 21356873 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21422419) 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, 3570399 + ... + 3570404.

It is an arithmetic number, because the mean of its divisors is an integer number (7140804).

Almost surely, 2^21422409 is an apocalyptic number.

It is an amenable number.

21422409 is a deficient number, since it is larger than the sum of its proper divisors (7140807).

21422409 is an equidigital number, since it uses as much as digits as its factorization.

21422409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7140806.

The product of its (nonzero) digits is 1152, while the sum is 24.

The square root of 21422409 is about 4628.4348326405. The cubic root of 21422409 is about 277.7299838423.

It can be divided in two parts, 2142 and 2409, that multiplied together give a triangular number (5160078 = T₃₂₁₂).

The spelling of 21422409 in words is "twenty-one million, four hundred twenty-two thousand, four hundred nine".