21768416 has 12 divisors (see below), whose sum is σ = 42856632. Its totient is φ = 10884192.

The previous prime is 21768407. The next prime is 21768431. The reversal of 21768416 is 61486712.

It is a Smith number, since the sum of its digits (35) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340100 + ... + 340163.

It is an arithmetic number, because the mean of its divisors is an integer number (3571386).

Almost surely, 2^21768416 is an apocalyptic number.

It is an amenable number.

21768416 is a deficient number, since it is larger than the sum of its proper divisors (21088216).

21768416 is an equidigital number, since it uses as much as digits as its factorization.

21768416 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 680273 (or 680265 counting only the distinct ones).

The product of its digits is 16128, while the sum is 35.

The square root of 21768416 is about 4665.6635112275. The cubic root of 21768416 is about 279.2172697259.

The spelling of 21768416 in words is "twenty-one million, seven hundred sixty-eight thousand, four hundred sixteen".