21798506 has 16 divisors (see below), whose sum is σ = 34176384. Its totient is φ = 10417344.

The previous prime is 21798499. The next prime is 21798509. The reversal of 21798506 is 60589712.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21798506.

It is not an unprimeable number, because it can be changed into a prime (21798509) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1346 + ... + 6738.

It is an arithmetic number, because the mean of its divisors is an integer number (2136024).

Almost surely, 2^21798506 is an apocalyptic number.

21798506 is a deficient number, since it is larger than the sum of its proper divisors (12377878).

21798506 is a wasteful number, since it uses less digits than its factorization.

21798506 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5485.

The product of its (nonzero) digits is 30240, while the sum is 38.

The square root of 21798506 is about 4668.8870194084. The cubic root of 21798506 is about 279.3458624461.

The spelling of 21798506 in words is "twenty-one million, seven hundred ninety-eight thousand, five hundred six".