21102551 has 8 divisors (see below), whose sum is σ = 21661200. Its totient is φ = 20547072.

The previous prime is 21102547. The next prime is 21102581. The reversal of 21102551 is 15520112.

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 21102551 - 2² = 21102547 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21102541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18761 + ... + 19853.

It is an arithmetic number, because the mean of its divisors is an integer number (2707650).

Almost surely, 2^21102551 is an apocalyptic number.

21102551 is a deficient number, since it is larger than the sum of its proper divisors (558649).

21102551 is a wasteful number, since it uses less digits than its factorization.

21102551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1585.

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

The square root of 21102551 is about 4593.7512993195. The cubic root of 21102551 is about 276.3407845052.

Adding to 21102551 its reverse (15520112), we get a palindrome (36622663).

The spelling of 21102551 in words is "twenty-one million, one hundred two thousand, five hundred fifty-one".