21031200 has 216 divisors, whose sum is σ = 77995008. Its totient is φ = 5322240.

The previous prime is 21031187. The next prime is 21031217. The reversal of 21031200 is 213012.

It is a happy number.

It is a super-2 number, since 2×21031200² = 884622746880000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 165537 + ... + 165663.

It is an arithmetic number, because the mean of its divisors is an integer number (361088).

Almost surely, 2^21031200 is an apocalyptic number.

21031200 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 21031200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38997504).

21031200 is an abundant number, since it is smaller than the sum of its proper divisors (56963808).

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

21031200 is a wasteful number, since it uses less digits than its factorization.

21031200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 176 (or 160 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 9.

The square root of 21031200 is about 4585.9786305651. The cubic root of 21031200 is about 276.0289824637.

Adding to 21031200 its reverse (213012), we get a palindrome (21244212).

The spelling of 21031200 in words is "twenty-one million, thirty-one thousand, two hundred".