21956320 has 48 divisors (see below), whose sum is σ = 53152848. Its totient is φ = 8565760.

The previous prime is 21956317. The next prime is 21956321. The reversal of 21956320 is 2365912.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21956321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4887 + ... + 8233.

It is an arithmetic number, because the mean of its divisors is an integer number (1107351).

Almost surely, 2^21956320 is an apocalyptic number.

21956320 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 21956320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26576424).

21956320 is an abundant number, since it is smaller than the sum of its proper divisors (31196528).

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

21956320 is a wasteful number, since it uses less digits than its factorization.

21956320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3403 (or 3395 counting only the distinct ones).

The product of its (nonzero) digits is 3240, while the sum is 28.

The square root of 21956320 is about 4685.7571426612. The cubic root of 21956320 is about 280.0183661422.

It can be divided in two parts, 2195 and 6320, that added together give a triangular number (8515 = T₁₃₀).

The spelling of 21956320 in words is "twenty-one million, nine hundred fifty-six thousand, three hundred twenty".