21810016 has 12 divisors (see below), whose sum is σ = 42938532. Its totient is φ = 10904992.

The previous prime is 21810013. The next prime is 21810029. The reversal of 21810016 is 61001812.

It is a junction number, because it is equal to n+sod(n) for n = 21809975 and 21810002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21810011) by changing a digit.

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 as a sum of consecutive naturals, namely, 340750 + ... + 340813.

It is an arithmetic number, because the mean of its divisors is an integer number (3578211).

Almost surely, 2^21810016 is an apocalyptic number.

It is an amenable number.

21810016 is a deficient number, since it is larger than the sum of its proper divisors (21128516).

21810016 is an equidigital number, since it uses as much as digits as its factorization.

21810016 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 681573 (or 681565 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 19.

The square root of 21810016 is about 4670.1194845528. The cubic root of 21810016 is about 279.3950203277.

Adding to 21810016 its reverse (61001812), we get a palindrome (82811828).

The spelling of 21810016 in words is "twenty-one million, eight hundred ten thousand, sixteen".