21967009 has 4 divisors (see below), whose sum is σ = 23259204. Its totient is φ = 20674816.

The previous prime is 21966961. The next prime is 21967019. The reversal of 21967009 is 90076912.

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 20277009 + 1690000 = 4503^2 + 1300^2 .

It is a cyclic number.

It is not a de Polignac number, because 21967009 - 2¹³ = 21958817 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21967019) 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, 646072 + ... + 646105.

It is an arithmetic number, because the mean of its divisors is an integer number (5814801).

Almost surely, 2^21967009 is an apocalyptic number.

It is an amenable number.

21967009 is a deficient number, since it is larger than the sum of its proper divisors (1292195).

21967009 is a wasteful number, since it uses less digits than its factorization.

21967009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1292194.

The product of its (nonzero) digits is 6804, while the sum is 34.

The square root of 21967009 is about 4686.8975879573. The cubic root of 21967009 is about 280.0637992375.

The spelling of 21967009 in words is "twenty-one million, nine hundred sixty-seven thousand, nine".