21426409 has 8 divisors (see below), whose sum is σ = 23673600. Its totient is φ = 19288896.

The previous prime is 21426401. The next prime is 21426413. The reversal of 21426409 is 90462412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21426409 - 2³ = 21426401 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21426401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 27009 + ... + 27790.

It is an arithmetic number, because the mean of its divisors is an integer number (2959200).

Almost surely, 2^21426409 is an apocalyptic number.

It is an amenable number.

21426409 is a deficient number, since it is larger than the sum of its proper divisors (2247191).

21426409 is a wasteful number, since it uses less digits than its factorization.

21426409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54839.

The product of its (nonzero) digits is 3456, while the sum is 28.

The square root of 21426409 is about 4628.8669239891. The cubic root of 21426409 is about 277.7472687144.

The spelling of 21426409 in words is "twenty-one million, four hundred twenty-six thousand, four hundred nine".