20871240 has 128 divisors (see below), whose sum is σ = 71487360. Its totient is φ = 4829184.

The previous prime is 20871229. The next prime is 20871251. The reversal of 20871240 is 4217802.

It is an interprime number because it is at equal distance from previous prime (20871229) and next prime (20871251).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 20871240.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 26127 + ... + 26913.

It is an arithmetic number, because the mean of its divisors is an integer number (558495).

Almost surely, 2^20871240 is an apocalyptic number.

20871240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20871240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35743680).

20871240 is an abundant number, since it is smaller than the sum of its proper divisors (50616120).

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

20871240 is a wasteful number, since it uses less digits than its factorization.

20871240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 831 (or 827 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 24.

The square root of 20871240 is about 4568.5052260012. The cubic root of 20871240 is about 275.3273896996.

The spelling of 20871240 in words is "twenty million, eight hundred seventy-one thousand, two hundred forty".