21383780 has 72 divisors (see below), whose sum is σ = 51057216. Its totient is φ = 7459200.

The previous prime is 21383777. The next prime is 21383833. The reversal of 21383780 is 8738312.

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, 301145 + ... + 301215.

It is an arithmetic number, because the mean of its divisors is an integer number (709128).

Almost surely, 2^21383780 is an apocalyptic number.

21383780 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 21383780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25528608).

21383780 is an abundant number, since it is smaller than the sum of its proper divisors (29673436).

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

21383780 is a wasteful number, since it uses less digits than its factorization.

21383780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165 (or 126 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 32.

The square root of 21383780 is about 4624.2599407905. The cubic root of 21383780 is about 277.5629486825.

The spelling of 21383780 in words is "twenty-one million, three hundred eighty-three thousand, seven hundred eighty".