21147836 has 12 divisors (see below), whose sum is σ = 38956680. Its totient is φ = 10017360.

The previous prime is 21147829. The next prime is 21147839. The reversal of 21147836 is 63874112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21147839) 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, 139055 + ... + 139206.

It is an arithmetic number, because the mean of its divisors is an integer number (3246390).

Almost surely, 2^21147836 is an apocalyptic number.

It is an amenable number.

21147836 is a deficient number, since it is larger than the sum of its proper divisors (17808844).

21147836 is a wasteful number, since it uses less digits than its factorization.

21147836 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 278284 (or 278282 counting only the distinct ones).

The product of its digits is 8064, while the sum is 32.

The square root of 21147836 is about 4598.6776360167. The cubic root of 21147836 is about 276.5383143607.

The spelling of 21147836 in words is "twenty-one million, one hundred forty-seven thousand, eight hundred thirty-six".