21102109 has 16 divisors (see below), whose sum is σ = 25650432. Its totient is φ = 16967808.

The previous prime is 21102101. The next prime is 21102113. The reversal of 21102109 is 90120112.

It is a cyclic number.

It is not a de Polignac number, because 21102109 - 2³ = 21102101 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21102092 and 21102101.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21102101) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7297 + ... + 9769.

It is an arithmetic number, because the mean of its divisors is an integer number (1603152).

Almost surely, 2^21102109 is an apocalyptic number.

It is an amenable number.

21102109 is a deficient number, since it is larger than the sum of its proper divisors (4548323).

21102109 is a wasteful number, since it uses less digits than its factorization.

21102109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2556.

The product of its (nonzero) digits is 36, while the sum is 16.

The square root of 21102109 is about 4593.7031902377. The cubic root of 21102109 is about 276.3388551416.

The spelling of 21102109 in words is "twenty-one million, one hundred two thousand, one hundred nine".