20831860 has 72 divisors (see below), whose sum is σ = 52715880. Its totient is φ = 6886656.

The previous prime is 20831849. The next prime is 20831861. The reversal of 20831860 is 6813802.

It can be written as a sum of positive squares in 4 ways, for example, as 7683984 + 13147876 = 2772^2 + 3626^2 .

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20831861) 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, 28054 + ... + 28786.

It is an arithmetic number, because the mean of its divisors is an integer number (732165).

Almost surely, 2^20831860 is an apocalyptic number.

20831860 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 20831860, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26357940).

20831860 is an abundant number, since it is smaller than the sum of its proper divisors (31884020).

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

20831860 is a wasteful number, since it uses less digits than its factorization.

20831860 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 785 (or 776 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 28.

The square root of 20831860 is about 4564.1932474425. The cubic root of 20831860 is about 275.1541174690.

The spelling of 20831860 in words is "twenty million, eight hundred thirty-one thousand, eight hundred sixty".