21661033032320 has 384 divisors, whose sum is σ = 58358347058880. Its totient is φ = 7683554672640.

The previous prime is 21661033032293. The next prime is 21661033032329. The reversal of 21661033032320 is 2323033016612.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is not an unprimeable number, because it can be changed into a prime (21661033032329) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 28167792896 + ... + 28167793664.

Almost surely, 2^{21661033032320} is an apocalyptic number.

21661033032320 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 21661033032320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29179173529440).

21661033032320 is an abundant number, since it is smaller than the sum of its proper divisors (36697314026560).

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

21661033032320 is an frugal number, since it uses more digits than its factorization.

21661033032320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1633 (or 830 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 32.

Adding to 21661033032320 its reverse (2323033016612), we get a palindrome (23984066048932).

The spelling of 21661033032320 in words is "twenty-one trillion, six hundred sixty-one billion, thirty-three million, thirty-two thousand, three hundred twenty".