21809099 has 8 divisors (see below), whose sum is σ = 23533440. Its totient is φ = 20091456.

The previous prime is 21809087. The next prime is 21809101. The reversal of 21809099 is 99090812.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21809099 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21809009) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6662 + ... + 9380.

It is an arithmetic number, because the mean of its divisors is an integer number (2941680).

Almost surely, 2^21809099 is an apocalyptic number.

21809099 is a deficient number, since it is larger than the sum of its proper divisors (1724341).

21809099 is a wasteful number, since it uses less digits than its factorization.

21809099 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3349.

The product of its (nonzero) digits is 11664, while the sum is 38.

The square root of 21809099 is about 4670.0213061612. The cubic root of 21809099 is about 279.3911045607.

The spelling of 21809099 in words is "twenty-one million, eight hundred nine thousand, ninety-nine".