21816055 has 8 divisors (see below), whose sum is σ = 26236800. Its totient is φ = 17414496.

The previous prime is 21816031. The next prime is 21816079. The reversal of 21816055 is 55061812.

It is an interprime number because it is at equal distance from previous prime (21816031) and next prime (21816079).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21816055 - 2¹⁵ = 21783287 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2160 + ... + 6949.

It is an arithmetic number, because the mean of its divisors is an integer number (3279600).

Almost surely, 2^21816055 is an apocalyptic number.

21816055 is a deficient number, since it is larger than the sum of its proper divisors (4420745).

21816055 is an equidigital number, since it uses as much as digits as its factorization.

21816055 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9593.

The product of its (nonzero) digits is 2400, while the sum is 28.

The square root of 21816055 is about 4670.7659971358. The cubic root of 21816055 is about 279.4208052824.

Adding to 21816055 its reverse (55061812), we get a palindrome (76877867).

The spelling of 21816055 in words is "twenty-one million, eight hundred sixteen thousand, fifty-five".