21748655 has 16 divisors (see below), whose sum is σ = 26901504. Its totient is φ = 16869120.

The previous prime is 21748651. The next prime is 21748687. The reversal of 21748655 is 55684712.

It is not a de Polignac number, because 21748655 - 2² = 21748651 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21748651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 56594 + ... + 56976.

It is an arithmetic number, because the mean of its divisors is an integer number (1681344).

Almost surely, 2^21748655 is an apocalyptic number.

21748655 is a deficient number, since it is larger than the sum of its proper divisors (5152849).

21748655 is a wasteful number, since it uses less digits than its factorization.

21748655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 706.

The product of its digits is 67200, while the sum is 38.

The square root of 21748655 is about 4663.5453251791. The cubic root of 21748655 is about 279.1327545747.

The spelling of 21748655 in words is "twenty-one million, seven hundred forty-eight thousand, six hundred fifty-five".