21693320 has 64 divisors (see below), whose sum is σ = 54432000. Its totient is φ = 7713280.

The previous prime is 21693319. The next prime is 21693323. The reversal of 21693320 is 2339612.

It is a self number, because there is not a number n which added to its sum of digits gives 21693320.

It is not an unprimeable number, because it can be changed into a prime (21693323) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20156 + ... + 21204.

It is an arithmetic number, because the mean of its divisors is an integer number (850500).

Almost surely, 2^21693320 is an apocalyptic number.

21693320 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 21693320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27216000).

21693320 is an abundant number, since it is smaller than the sum of its proper divisors (32738680).

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

21693320 is a wasteful number, since it uses less digits than its factorization.

21693320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1118 (or 1114 counting only the distinct ones).

The product of its (nonzero) digits is 1944, while the sum is 26.

The square root of 21693320 is about 4657.6088285729. The cubic root of 21693320 is about 278.8958214695.

The spelling of 21693320 in words is "twenty-one million, six hundred ninety-three thousand, three hundred twenty".