21621404554420 has 192 divisors, whose sum is σ = 50290595712000. Its totient is φ = 7742972160000.

The previous prime is 21621404554411. The next prime is 21621404554423. The reversal of 21621404554420 is 2445540412612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21621404554423) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3342306946 + ... + 3342313414.

It is an arithmetic number, because the mean of its divisors is an integer number (261930186000).

Almost surely, 2^{21621404554420} is an apocalyptic number.

21621404554420 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 21621404554420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25145297856000).

21621404554420 is an abundant number, since it is smaller than the sum of its proper divisors (28669191157580).

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

21621404554420 is a wasteful number, since it uses less digits than its factorization.

21621404554420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7370 (or 7368 counting only the distinct ones).

The product of its (nonzero) digits is 307200, while the sum is 40.

The spelling of 21621404554420 in words is "twenty-one trillion, six hundred twenty-one billion, four hundred four million, five hundred fifty-four thousand, four hundred twenty".