21206793888 has 216 divisors, whose sum is σ = 74280309012. Its totient is φ = 5702602752.

The previous prime is 21206793869. The next prime is 21206793889. The reversal of 21206793888 is 88839760212.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 21191207184 + 15586704 = 145572^2 + 3948^2 .

It is a super-2 number, since 2×21206793888² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21206793889) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 195706 + ... + 284102.

Almost surely, 2^21206793888 is an apocalyptic number.

21206793888 is a gapful number since it is divisible by the number (28) 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 21206793888, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37140154506).

21206793888 is an abundant number, since it is smaller than the sum of its proper divisors (53073515124).

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

21206793888 is a wasteful number, since it uses less digits than its factorization.

21206793888 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88444 (or 88426 counting only the distinct ones).

The product of its (nonzero) digits is 2322432, while the sum is 54.

The spelling of 21206793888 in words is "twenty-one billion, two hundred six million, seven hundred ninety-three thousand, eight hundred eighty-eight".