21621622400 has 192 divisors, whose sum is σ = 62291400000. Its totient is φ = 7412751360.

The previous prime is 21621622343. The next prime is 21621622409. The reversal of 21621622400 is 422612612.

It is a self number, because there is not a number n which added to its sum of digits gives 21621622400.

It is not an unprimeable number, because it can be changed into a prime (21621622409) 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, 1087751 + ... + 1107449.

It is an arithmetic number, because the mean of its divisors is an integer number (324434375).

Almost surely, 2^21621622400 is an apocalyptic number.

21621622400 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 21621622400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31145700000).

21621622400 is an abundant number, since it is smaller than the sum of its proper divisors (40669777600).

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

21621622400 is an equidigital number, since it uses as much as digits as its factorization.

21621622400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19744 (or 19713 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 26.

The spelling of 21621622400 in words is "twenty-one billion, six hundred twenty-one million, six hundred twenty-two thousand, four hundred".