21023815680 has 1152 divisors, whose sum is σ = 92726000640. Its totient is φ = 4459069440.

The previous prime is 21023815619. The next prime is 21023815699. The reversal of 21023815680 is 8651832012.

It is a happy number.

21023815680 is a `hidden beast` number, since 2 + 10 + 2 + 3 + 81 + 568 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (1152).

It is a super-2 number, since 2×21023815680² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 296110045 + ... + 296110115.

It is an arithmetic number, because the mean of its divisors is an integer number (80491320).

Almost surely, 2^21023815680 is an apocalyptic number.

21023815680 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 21023815680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (46363000320).

21023815680 is an abundant number, since it is smaller than the sum of its proper divisors (71702184960).

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

21023815680 is an equidigital number, since it uses as much as digits as its factorization.

21023815680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 137 (or 105 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 36.

The spelling of 21023815680 in words is "twenty-one billion, twenty-three million, eight hundred fifteen thousand, six hundred eighty".