21809098 has 4 divisors (see below), whose sum is σ = 32713650. Its totient is φ = 10904548.

The previous prime is 21809087. The next prime is 21809101. The reversal of 21809098 is 89090812.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 12341169 + 9467929 = 3513^2 + 3077^2 .

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 5452273 + ... + 5452276.

Almost surely, 2^21809098 is an apocalyptic number.

21809098 is a deficient number, since it is larger than the sum of its proper divisors (10904552).

21809098 is a wasteful number, since it uses less digits than its factorization.

21809098 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10904551.

The product of its (nonzero) digits is 10368, while the sum is 37.

The square root of 21809098 is about 4670.0211990954. The cubic root of 21809098 is about 279.3911002905.

The spelling of 21809098 in words is "twenty-one million, eight hundred nine thousand, ninety-eight".