21067021 has 8 divisors (see below), whose sum is σ = 22152600. Its totient is φ = 20005440.

The previous prime is 21067019. The next prime is 21067031. The reversal of 21067021 is 12076012.

It can be written as a sum of positive squares in 4 ways, for example, as 8100 + 21058921 = 90^2 + 4589^2 .

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 21067021 - 2¹ = 21067019 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21067021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21067031) 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 7 ways as a sum of consecutive naturals, for example, 4186 + ... + 7723.

It is an arithmetic number, because the mean of its divisors is an integer number (2769075).

Almost surely, 2^21067021 is an apocalyptic number.

It is an amenable number.

21067021 is a deficient number, since it is larger than the sum of its proper divisors (1085579).

21067021 is a wasteful number, since it uses less digits than its factorization.

21067021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11999.

The product of its (nonzero) digits is 168, while the sum is 19.

The square root of 21067021 is about 4589.8824603687. The cubic root of 21067021 is about 276.1856073170.

The spelling of 21067021 in words is "twenty-one million, sixty-seven thousand, twenty-one".