21647870400 has 756 divisors, whose sum is σ = 83411833176. Its totient is φ = 4885401600.

The previous prime is 21647870371. The next prime is 21647870401. The reversal of 21647870400 is 407874612.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21647870401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 107 ways as a sum of consecutive naturals, for example, 698318385 + ... + 698318415.

Almost surely, 2^21647870400 is an apocalyptic number.

21647870400 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 21647870400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41705916588).

21647870400 is an abundant number, since it is smaller than the sum of its proper divisors (61763962776).

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

21647870400 is a wasteful number, since it uses less digits than its factorization.

21647870400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 138 (or 73 counting only the distinct ones).

The product of its (nonzero) digits is 75264, while the sum is 39.

Multiplying 21647870400 by its sum of digits (39), we get a square (844266945600 = 918840²).

21647870400 divided by its sum of digits (39) gives a square (555073600 = 23560²).

The spelling of 21647870400 in words is "twenty-one billion, six hundred forty-seven million, eight hundred seventy thousand, four hundred".