21102155 has 8 divisors (see below), whose sum is σ = 26423712. Its totient is φ = 16147648.

The previous prime is 21102113. The next prime is 21102161. The reversal of 21102155 is 55120112.

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

It is a cyclic number.

It is not a de Polignac number, because 21102155 - 2⁶ = 21102091 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 91634 + ... + 91863.

It is an arithmetic number, because the mean of its divisors is an integer number (3302964).

Almost surely, 2^21102155 is an apocalyptic number.

21102155 is a deficient number, since it is larger than the sum of its proper divisors (5321557).

21102155 is a wasteful number, since it uses less digits than its factorization.

21102155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 183525.

The product of its (nonzero) digits is 100, while the sum is 17.

The square root of 21102155 is about 4593.7081970887. The cubic root of 21102155 is about 276.3390559364.

Adding to 21102155 its reverse (55120112), we get a palindrome (76222267).

The spelling of 21102155 in words is "twenty-one million, one hundred two thousand, one hundred fifty-five".