21917312 has 32 divisors (see below), whose sum is σ = 44210880. Its totient is φ = 10821376.

The previous prime is 21917281. The next prime is 21917333. The reversal of 21917312 is 21371912.

It is a tau number, because it is divible by the number of its divisors (32).

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 9593 + ... + 11655.

It is an arithmetic number, because the mean of its divisors is an integer number (1381590).

Almost surely, 2^21917312 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 21917312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22105440).

21917312 is an abundant number, since it is smaller than the sum of its proper divisors (22293568).

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

21917312 is an equidigital number, since it uses as much as digits as its factorization.

21917312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2160 (or 2148 counting only the distinct ones).

The product of its digits is 756, while the sum is 26.

The square root of 21917312 is about 4681.5928913138. The cubic root of 21917312 is about 279.8524392556.

The spelling of 21917312 in words is "twenty-one million, nine hundred seventeen thousand, three hundred twelve".