21808898 has 16 divisors (see below), whose sum is σ = 33492480. Its totient is φ = 10647936.

The previous prime is 21808889. The next prime is 21808921. The reversal of 21808898 is 89880812.

It is a Smith number, since the sum of its digits (44) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Curzon 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, 14615 + ... + 16037.

It is an arithmetic number, because the mean of its divisors is an integer number (2093280).

Almost surely, 2^21808898 is an apocalyptic number.

21808898 is a deficient number, since it is larger than the sum of its proper divisors (11683582).

21808898 is a wasteful number, since it uses less digits than its factorization.

21808898 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1601.

The product of its (nonzero) digits is 73728, while the sum is 44.

The square root of 21808898 is about 4669.9997858672. Note that the first 3 decimals coincide. The cubic root of 21808898 is about 279.3902462372.

The spelling of 21808898 in words is "twenty-one million, eight hundred eight thousand, eight hundred ninety-eight".