21871247 has 8 divisors (see below), whose sum is σ = 22362480. Its totient is φ = 21385600.

The previous prime is 21871243. The next prime is 21871253. The reversal of 21871247 is 74217812.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21871247 - 2² = 21871243 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 (21871243) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7079 + ... + 9687.

It is an arithmetic number, because the mean of its divisors is an integer number (2795310).

Almost surely, 2^21871247 is an apocalyptic number.

21871247 is a deficient number, since it is larger than the sum of its proper divisors (491233).

21871247 is a wasteful number, since it uses less digits than its factorization.

21871247 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2793.

The product of its digits is 6272, while the sum is 32.

The square root of 21871247 is about 4676.6705036810. The cubic root of 21871247 is about 279.6562405500.

The spelling of 21871247 in words is "twenty-one million, eight hundred seventy-one thousand, two hundred forty-seven".