20871647 has 8 divisors (see below), whose sum is σ = 21159600. Its totient is φ = 20585664.

The previous prime is 20871637. The next prime is 20871659. The reversal of 20871647 is 74617802.

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 20871647 - 2¹⁰ = 20870623 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 (20871637) 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, 45443 + ... + 45899.

It is an arithmetic number, because the mean of its divisors is an integer number (2644950).

Almost surely, 2^20871647 is an apocalyptic number.

20871647 is a deficient number, since it is larger than the sum of its proper divisors (287953).

20871647 is a wasteful number, since it uses less digits than its factorization.

20871647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 985.

The product of its (nonzero) digits is 18816, while the sum is 35.

The square root of 20871647 is about 4568.5497698942. The cubic root of 20871647 is about 275.3291793636.

The spelling of 20871647 in words is "twenty million, eight hundred seventy-one thousand, six hundred forty-seven".