21306842 has 8 divisors (see below), whose sum is σ = 32085396. Its totient is φ = 10611712.

The previous prime is 21306823. The next prime is 21306869. The reversal of 21306842 is 24860312.

It can be written as a sum of positive squares in 2 ways, for example, as 21169201 + 137641 = 4601^2 + 371^2 .

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 (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20213 + ... + 21240.

Almost surely, 2^21306842 is an apocalyptic number.

21306842 is a deficient number, since it is larger than the sum of its proper divisors (10778554).

21306842 is a wasteful number, since it uses less digits than its factorization.

21306842 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41712.

The product of its (nonzero) digits is 2304, while the sum is 26.

The square root of 21306842 is about 4615.9334917219. The cubic root of 21306842 is about 277.2296617845.

The spelling of 21306842 in words is "twenty-one million, three hundred six thousand, eight hundred forty-two".