21286100 has 72 divisors (see below), whose sum is σ = 51850848. Its totient is φ = 7516800.

The previous prime is 21286081. The next prime is 21286103. The reversal of 21286100 is 168212.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21286103) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 40439 + ... + 40961.

Almost surely, 2^21286100 is an apocalyptic number.

21286100 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 21286100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25925424).

21286100 is an abundant number, since it is smaller than the sum of its proper divisors (30564748).

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

21286100 is a wasteful number, since it uses less digits than its factorization.

21286100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 585 (or 578 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 20.

The square root of 21286100 is about 4613.6861618450. The cubic root of 21286100 is about 277.1396724654.

It can be divided in two parts, 2128 and 6100, that added together give a palindrome (8228).

The spelling of 21286100 in words is "twenty-one million, two hundred eighty-six thousand, one hundred".