21388989600 has 720 divisors, whose sum is σ = 87500087136. Its totient is φ = 5038848000.

The previous prime is 21388989577. The next prime is 21388989653. The reversal of 21388989600 is 698988312.

It is a happy number.

21388989600 is a `hidden beast` number, since 21 + 3 + 8 + 8 + 9 + 8 + 9 + 600 = 666.

It is a tau number, because it is divible by the number of its divisors (720).

It is a super-2 number, since 2×21388989600² (a number of 21 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 26373195 + ... + 26374005.

Almost surely, 2^21388989600 is an apocalyptic number.

21388989600 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 21388989600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43750043568).

21388989600 is an abundant number, since it is smaller than the sum of its proper divisors (66111097536).

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

21388989600 is a wasteful number, since it uses less digits than its factorization.

21388989600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 891 (or 869 counting only the distinct ones).

The product of its (nonzero) digits is 1492992, while the sum is 54.

The spelling of 21388989600 in words is "twenty-one billion, three hundred eighty-eight million, nine hundred eighty-nine thousand, six hundred".