21776916 has 48 divisors (see below), whose sum is σ = 58544640. Its totient is φ = 6171360.

The previous prime is 21776899. The next prime is 21776917. The reversal of 21776916 is 61967712.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21776917) 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, 10015 + ... + 11993.

It is an arithmetic number, because the mean of its divisors is an integer number (1219680).

Almost surely, 2^21776916 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 21776916, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29272320).

21776916 is an abundant number, since it is smaller than the sum of its proper divisors (36767724).

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

21776916 is a wasteful number, since it uses less digits than its factorization.

21776916 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2124 (or 2122 counting only the distinct ones).

The product of its digits is 31752, while the sum is 39.

The square root of 21776916 is about 4666.5743324199. The cubic root of 21776916 is about 279.2536073561.

The spelling of 21776916 in words is "twenty-one million, seven hundred seventy-six thousand, nine hundred sixteen".