21142247 has 8 divisors (see below), whose sum is σ = 24996000. Its totient is φ = 17496864.

The previous prime is 21142243. The next prime is 21142259. The reversal of 21142247 is 74224112.

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

It is not a de Polignac number, because 21142247 - 2² = 21142243 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21142243) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 51872 + ... + 52277.

It is an arithmetic number, because the mean of its divisors is an integer number (3124500).

Almost surely, 2^21142247 is an apocalyptic number.

21142247 is a deficient number, since it is larger than the sum of its proper divisors (3853753).

21142247 is a wasteful number, since it uses less digits than its factorization.

21142247 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 104185.

The product of its digits is 896, while the sum is 23.

The square root of 21142247 is about 4598.0699211734. The cubic root of 21142247 is about 276.5139508149.

Adding to 21142247 its reverse (74224112), we get a palindrome (95366359).

The spelling of 21142247 in words is "twenty-one million, one hundred forty-two thousand, two hundred forty-seven".