21190400 has 216 divisors, whose sum is σ = 66912384. Its totient is φ = 6451200.

The previous prime is 21190349. The next prime is 21190409. The reversal of 21190400 is 409112.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21190409) 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, 492779 + ... + 492821.

Almost surely, 2^21190400 is an apocalyptic number.

21190400 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 21190400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33456192).

21190400 is an abundant number, since it is smaller than the sum of its proper divisors (45721984).

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

21190400 is a wasteful number, since it uses less digits than its factorization.

21190400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87 (or 68 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 17.

The square root of 21190400 is about 4603.3031618611. The cubic root of 21190400 is about 276.7237184969.

Adding to 21190400 its reverse (409112), we get a palindrome (21599512).

The spelling of 21190400 in words is "twenty-one million, one hundred ninety thousand, four hundred".