21993905280 has 128 divisors (see below), whose sum is σ = 70190377920. Its totient is φ = 5857947648.

The previous prime is 21993905249. The next prime is 21993905293. The reversal of 21993905280 is 8250939912.

It is a tau number, because it is divible by the number of its divisors (128).

It is a super-2 number, since 2×21993905280² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1688874 + ... + 1701846.

Almost surely, 2^21993905280 is an apocalyptic number.

21993905280 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 21993905280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35095188960).

21993905280 is an abundant number, since it is smaller than the sum of its proper divisors (48196472640).

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

21993905280 is a wasteful number, since it uses less digits than its factorization.

21993905280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13878 (or 13866 counting only the distinct ones).

The product of its (nonzero) digits is 349920, while the sum is 48.

The spelling of 21993905280 in words is "twenty-one billion, nine hundred ninety-three million, nine hundred five thousand, two hundred eighty".