21228197760 has 768 divisors, whose sum is σ = 95410897920. Its totient is φ = 4217241600.

The previous prime is 21228197713. The next prime is 21228197797. The reversal of 21228197760 is 6779182212.

It is a happy number.

21228197760 is a `hidden beast` number, since 212 + 281 + 97 + 76 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

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, 10199920 + ... + 10202000.

It is an arithmetic number, because the mean of its divisors is an integer number (124232940).

Almost surely, 2^21228197760 is an apocalyptic number.

21228197760 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 21228197760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (47705448960).

21228197760 is an abundant number, since it is smaller than the sum of its proper divisors (74182700160).

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

21228197760 is a wasteful number, since it uses less digits than its factorization.

21228197760 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2147 (or 2132 counting only the distinct ones).

The product of its (nonzero) digits is 169344, while the sum is 45.

The spelling of 21228197760 in words is "twenty-one billion, two hundred twenty-eight million, one hundred ninety-seven thousand, seven hundred sixty".