21320010400 has 144 divisors (see below), whose sum is σ = 56161889784. Its totient is φ = 7856455680.

The previous prime is 21320010377. The next prime is 21320010407. The reversal of 21320010400 is 401002312.

It can be written as a sum of positive squares in 12 ways, for example, as 1006919824 + 20313090576 = 31732^2 + 142524^2 .

It is a super-2 number, since 2×21320010400² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (13).

It is not an unprimeable number, because it can be changed into a prime (21320010407) 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, 6165472 + ... + 6168928.

Almost surely, 2^21320010400 is an apocalyptic number.

21320010400 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 21320010400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28080944892).

21320010400 is an abundant number, since it is smaller than the sum of its proper divisors (34841879384).

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

21320010400 is a wasteful number, since it uses less digits than its factorization.

21320010400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4083 (or 4070 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 13.

Adding to 21320010400 its reverse (401002312), we get a palindrome (21721012712).

The spelling of 21320010400 in words is "twenty-one billion, three hundred twenty million, ten thousand, four hundred".