20871847 has 4 divisors (see below), whose sum is σ = 20882520. Its totient is φ = 20861176.

The previous prime is 20871769. The next prime is 20871853. The reversal of 20871847 is 74817802.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20871847 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 (20871857) 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, 1468 + ... + 6625.

It is an arithmetic number, because the mean of its divisors is an integer number (5220630).

Almost surely, 2^20871847 is an apocalyptic number.

20871847 is a deficient number, since it is larger than the sum of its proper divisors (10673).

20871847 is an equidigital number, since it uses as much as digits as its factorization.

20871847 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10672.

The product of its (nonzero) digits is 25088, while the sum is 37.

The square root of 20871847 is about 4568.5716586259. The cubic root of 20871847 is about 275.3300587968.

The spelling of 20871847 in words is "twenty million, eight hundred seventy-one thousand, eight hundred forty-seven".