21389760 has 168 divisors, whose sum is σ = 84161376. Its totient is φ = 4884480.

The previous prime is 21389743. The next prime is 21389773. The reversal of 21389760 is 6798312.

It is a tau number, because it is divible by the number of its divisors (168).

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 23 ways as a sum of consecutive naturals, for example, 19630 + ... + 20690.

Almost surely, 2^21389760 is an apocalyptic number.

21389760 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 21389760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42080688).

21389760 is an abundant number, since it is smaller than the sum of its proper divisors (62771616).

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

21389760 is a wasteful number, since it uses less digits than its factorization.

21389760 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1091 (or 1078 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 36.

The square root of 21389760 is about 4624.9064855411. The cubic root of 21389760 is about 277.5888198760.

The spelling of 21389760 in words is "twenty-one million, three hundred eighty-nine thousand, seven hundred sixty".