21147838 has 8 divisors (see below), whose sum is σ = 32396832. Its totient is φ = 10348896.

The previous prime is 21147829. The next prime is 21147839. The reversal of 21147838 is 83874112.

It is a happy number.

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

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 polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 112395 + ... + 112582.

It is an arithmetic number, because the mean of its divisors is an integer number (4049604).

Almost surely, 2^21147838 is an apocalyptic number.

21147838 is a deficient number, since it is larger than the sum of its proper divisors (11248994).

21147838 is a wasteful number, since it uses less digits than its factorization.

21147838 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 225026.

The product of its digits is 10752, while the sum is 34.

The square root of 21147838 is about 4598.6778534705. The cubic root of 21147838 is about 276.5383230783.

The spelling of 21147838 in words is "twenty-one million, one hundred forty-seven thousand, eight hundred thirty-eight".