20871684 has 72 divisors (see below), whose sum is σ = 54934880. Its totient is φ = 6676992.

The previous prime is 20871667. The next prime is 20871689. The reversal of 20871684 is 48617802.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (20871689) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 150087 + ... + 150225.

Almost surely, 2^20871684 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20871684, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27467440).

20871684 is an abundant number, since it is smaller than the sum of its proper divisors (34063196).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20871684 is a wasteful number, since it uses less digits than its factorization.

20871684 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 289 (or 284 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 36.

The square root of 20871684 is about 4568.5538193174. The cubic root of 20871684 is about 275.3293420591.

The spelling of 20871684 in words is "twenty million, eight hundred seventy-one thousand, six hundred eighty-four".