21397838400 has 567 divisors, whose sum is σ = 81031755259. Its totient is φ = 5355018240.

The previous prime is 21397838383. The next prime is 21397838401. The reversal of 21397838400 is 483879312.

The square root of 21397838400 is 146280.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 161188416 + 21236649984 = 12696^2 + 145728^2 .

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21397838401) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 403732774 + ... + 403732826.

Almost surely, 2^21397838400 is an apocalyptic number.

21397838400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

21397838400 is the 146280-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21397838400

21397838400 is an abundant number, since it is smaller than the sum of its proper divisors (59633916859).

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

21397838400 is a wasteful number, since it uses less digits than its factorization.

21397838400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180 (or 86 counting only the distinct ones).

The product of its (nonzero) digits is 290304, while the sum is 45.

The spelling of 21397838400 in words is "twenty-one billion, three hundred ninety-seven million, eight hundred thirty-eight thousand, four hundred".