21209618880 has 448 divisors, whose sum is σ = 79734948480. Its totient is φ = 5288951808.

The previous prime is 21209618839. The next prime is 21209618921. The reversal of 21209618880 is 8881690212.

It is a happy number.

21209618880 is a `hidden beast` number, since 2 + 1 + 20 + 9 + 618 + 8 + 8 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (21209618839) and next prime (21209618921).

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 pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 28934994 + ... + 28935726.

Almost surely, 2^21209618880 is an apocalyptic number.

21209618880 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 21209618880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39867474240).

21209618880 is an abundant number, since it is smaller than the sum of its proper divisors (58525329600).

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

21209618880 is a wasteful number, since it uses less digits than its factorization.

21209618880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 973 (or 957 counting only the distinct ones).

The product of its (nonzero) digits is 110592, while the sum is 45.

The spelling of 21209618880 in words is "twenty-one billion, two hundred nine million, six hundred eighteen thousand, eight hundred eighty".