21383680 has 40 divisors (see below), whose sum is σ = 51276852. Its totient is φ = 8552448.

The previous prime is 21383651. The next prime is 21383699. The reversal of 21383680 is 8638312.

It can be written as a sum of positive squares in 2 ways, for example, as 21381376 + 2304 = 4624^2 + 48^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a super-3 number, since 3×21383680³ (a number of 23 digits) contains 333 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1617 + ... + 6736.

Almost surely, 2^21383680 is an apocalyptic number.

21383680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21383680 is an abundant number, since it is smaller than the sum of its proper divisors (29893172).

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

21383680 is an frugal number, since it uses more digits than its factorization.

21383680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8376 (or 8360 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 31.

The square root of 21383680 is about 4624.2491282369. The cubic root of 21383680 is about 277.5625160128.

The spelling of 21383680 in words is "twenty-one million, three hundred eighty-three thousand, six hundred eighty".