21221134400 has 84 divisors (see below), whose sum is σ = 52272793092. Its totient is φ = 8479426560.

The previous prime is 21221134349. The next prime is 21221134411. The reversal of 21221134400 is 443112212.

It can be written as a sum of positive squares in 6 ways, for example, as 1594245184 + 19626889216 = 39928^2 + 140096^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1614254 + ... + 1627346.

Almost surely, 2^21221134400 is an apocalyptic number.

21221134400 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 21221134400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26136396546).

21221134400 is an abundant number, since it is smaller than the sum of its proper divisors (31051658692).

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

21221134400 is a wasteful number, since it uses less digits than its factorization.

21221134400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14128 (or 14113 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 20.

Adding to 21221134400 its reverse (443112212), we get a palindrome (21664246612).

The spelling of 21221134400 in words is "twenty-one billion, two hundred twenty-one million, one hundred thirty-four thousand, four hundred".