21653109 has 16 divisors (see below), whose sum is σ = 32607040. Its totient is φ = 14197680.

The previous prime is 21653101. The next prime is 21653129. The reversal of 21653109 is 90135612.

21653109 is a `hidden beast` number, since 2 + 1 + 653 + 1 + 0 + 9 = 666.

It is not a de Polignac number, because 21653109 - 2³ = 21653101 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21653101) 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 15 ways as a sum of consecutive naturals, for example, 4927 + ... + 8220.

It is an arithmetic number, because the mean of its divisors is an integer number (2037940).

Almost surely, 2^21653109 is an apocalyptic number.

It is an amenable number.

21653109 is a deficient number, since it is larger than the sum of its proper divisors (10953931).

21653109 is a wasteful number, since it uses less digits than its factorization.

21653109 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13217 (or 13211 counting only the distinct ones).

The product of its (nonzero) digits is 1620, while the sum is 27.

The square root of 21653109 is about 4653.2901263515. The cubic root of 21653109 is about 278.7233933328.

The spelling of 21653109 in words is "twenty-one million, six hundred fifty-three thousand, one hundred nine".