21005102 has 4 divisors (see below), whose sum is σ = 31507656. Its totient is φ = 10502550.

The previous prime is 21005087. The next prime is 21005111. The reversal of 21005102 is 20150012.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5251274 + ... + 5251277.

It is an arithmetic number, because the mean of its divisors is an integer number (7876914).

Almost surely, 2^21005102 is an apocalyptic number.

21005102 is a deficient number, since it is larger than the sum of its proper divisors (10502554).

21005102 is a wasteful number, since it uses less digits than its factorization.

21005102 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10502553.

The product of its (nonzero) digits is 20, while the sum is 11.

The square root of 21005102 is about 4583.1323349866. The cubic root of 21005102 is about 275.9147587355.

Adding to 21005102 its reverse (20150012), we get a palindrome (41155114).

The spelling of 21005102 in words is "twenty-one million, five thousand, one hundred two".