21661098 has 8 divisors (see below), whose sum is σ = 43322208. Its totient is φ = 7220364.

The previous prime is 21661097. The next prime is 21661109. The reversal of 21661098 is 89016612.

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

21661098 is an admirable number.

It is not an unprimeable number, because it can be changed into a prime (21661097) 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 in 3 ways as a sum of consecutive naturals, for example, 1805086 + ... + 1805097.

It is an arithmetic number, because the mean of its divisors is an integer number (5415276).

Almost surely, 2^21661098 is an apocalyptic number.

21661098 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21661098 is a wasteful number, since it uses less digits than its factorization.

21661098 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3610188.

The product of its (nonzero) digits is 5184, while the sum is 33.

The square root of 21661098 is about 4654.1484720623. The cubic root of 21661098 is about 278.7576678164.

The spelling of 21661098 in words is "twenty-one million, six hundred sixty-one thousand, ninety-eight".