21762816 has 72 divisors (see below), whose sum is σ = 59357760. Its totient is φ = 7074816.

The previous prime is 21762781. The next prime is 21762817. The reversal of 21762816 is 61826712.

It is not an unprimeable number, because it can be changed into a prime (21762817) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 32695 + ... + 33353.

Almost surely, 2^21762816 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 21762816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29678880).

21762816 is an abundant number, since it is smaller than the sum of its proper divisors (37594944).

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

21762816 is an equidigital number, since it uses as much as digits as its factorization.

21762816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 721 (or 707 counting only the distinct ones).

The product of its digits is 8064, while the sum is 33.

The square root of 21762816 is about 4665.0633436214. The cubic root of 21762816 is about 279.1933244710.

It can be divided in two parts, 21762 and 816, that added together give a triangular number (22578 = T₂₁₂).

The spelling of 21762816 in words is "twenty-one million, seven hundred sixty-two thousand, eight hundred sixteen".