21006107 has 4 divisors (see below), whose sum is σ = 21919440. Its totient is φ = 20092776.

The previous prime is 21006103. The next prime is 21006109. The reversal of 21006107 is 70160012.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21006107 - 2² = 21006103 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21006103) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 456632 + ... + 456677.

It is an arithmetic number, because the mean of its divisors is an integer number (5479860).

Almost surely, 2^21006107 is an apocalyptic number.

21006107 is a deficient number, since it is larger than the sum of its proper divisors (913333).

21006107 is an equidigital number, since it uses as much as digits as its factorization.

21006107 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 913332.

The product of its (nonzero) digits is 84, while the sum is 17.

The square root of 21006107 is about 4583.2419748471. The cubic root of 21006107 is about 275.9191590936.

Adding to 21006107 its reverse (70160012), we get a palindrome (91166119).

The spelling of 21006107 in words is "twenty-one million, six thousand, one hundred seven".