21012107 has 4 divisors (see below), whose sum is σ = 21138096. Its totient is φ = 20886120.

The previous prime is 21012091. The next prime is 21012127. The reversal of 21012107 is 70121012.

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 21012107 - 2⁴ = 21012091 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a plaindrome in base 13.

It is a junction number, because it is equal to n+sod(n) for n = 21012091 and 21012100.

It is not an unprimeable number, because it can be changed into a prime (21012127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 62744 + ... + 63077.

It is an arithmetic number, because the mean of its divisors is an integer number (5284524).

Almost surely, 2^21012107 is an apocalyptic number.

21012107 is a deficient number, since it is larger than the sum of its proper divisors (125989).

21012107 is a wasteful number, since it uses less digits than its factorization.

21012107 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 125988.

The product of its (nonzero) digits is 28, while the sum is 14.

The square root of 21012107 is about 4583.8964866149. The cubic root of 21012107 is about 275.9454269682.

Adding to 21012107 its reverse (70121012), we get a palindrome (91133119).

The spelling of 21012107 in words is "twenty-one million, twelve thousand, one hundred seven".