19921216 has 56 divisors (see below), whose sum is σ = 46085760. Its totient is φ = 8366592.

The previous prime is 19921211. The next prime is 19921217. The reversal of 19921216 is 61212991.

It is a tau number, because it is divible by the number of its divisors (56).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19921211) 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 7 ways as a sum of consecutive naturals, for example, 23325 + ... + 24163.

It is an arithmetic number, because the mean of its divisors is an integer number (822960).

Almost surely, 2^19921216 is an apocalyptic number.

19921216 is a gapful number since it is divisible by the number (16) 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 19921216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23042880).

19921216 is an abundant number, since it is smaller than the sum of its proper divisors (26164544).

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

19921216 is an equidigital number, since it uses as much as digits as its factorization.

19921216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 911 (or 901 counting only the distinct ones).

The product of its digits is 1944, while the sum is 31.

The square root of 19921216 is about 4463.3189444627. The cubic root of 19921216 is about 271.0848714987.

The spelling of 19921216 in words is "nineteen million, nine hundred twenty-one thousand, two hundred sixteen".