21956316 has 48 divisors (see below), whose sum is σ = 55528704. Its totient is φ = 6725376.

The previous prime is 21956303. The next prime is 21956317. The reversal of 21956316 is 61365912.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21956317) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7521 + ... + 10023.

It is an arithmetic number, because the mean of its divisors is an integer number (1156848).

Almost surely, 2^21956316 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21956316, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27764352).

21956316 is an abundant number, since it is smaller than the sum of its proper divisors (33572388).

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

21956316 is a wasteful number, since it uses less digits than its factorization.

21956316 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2570 (or 2568 counting only the distinct ones).

The product of its digits is 9720, while the sum is 33.

The square root of 21956316 is about 4685.7567158358. The cubic root of 21956316 is about 280.0183491376.

The spelling of 21956316 in words is "twenty-one million, nine hundred fifty-six thousand, three hundred sixteen".