21211400 has 96 divisors (see below), whose sum is σ = 57288000. Its totient is φ = 7153920.

The previous prime is 21211387. The next prime is 21211403. The reversal of 21211400 is 411212.

It is not an unprimeable number, because it can be changed into a prime (21211403) 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, 152531 + ... + 152669.

It is an arithmetic number, because the mean of its divisors is an integer number (596750).

Almost surely, 2^21211400 is an apocalyptic number.

21211400 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 21211400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28644000).

21211400 is an abundant number, since it is smaller than the sum of its proper divisors (36076600).

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

21211400 is a wasteful number, since it uses less digits than its factorization.

21211400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 271 (or 262 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 11.

The square root of 21211400 is about 4605.5835678012. The cubic root of 21211400 is about 276.8151007499.

Adding to 21211400 its reverse (411212), we get a palindrome (21622612).

The spelling of 21211400 in words is "twenty-one million, two hundred eleven thousand, four hundred".