21066394 has 8 divisors (see below), whose sum is σ = 32453748. Its totient is φ = 10248480.

The previous prime is 21066373. The next prime is 21066401. The reversal of 21066394 is 49366012.

It can be written as a sum of positive squares in 2 ways, for example, as 19035769 + 2030625 = 4363^2 + 1425^2 .

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

It is an unprimeable number.

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, 142267 + ... + 142414.

Almost surely, 2^21066394 is an apocalyptic number.

21066394 is a deficient number, since it is larger than the sum of its proper divisors (11387354).

21066394 is a wasteful number, since it uses less digits than its factorization.

21066394 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 284720.

The product of its (nonzero) digits is 7776, while the sum is 31.

The square root of 21066394 is about 4589.8141574578. The cubic root of 21066394 is about 276.1828673300.

The spelling of 21066394 in words is "twenty-one million, sixty-six thousand, three hundred ninety-four".