21012307 has 2 divisors, whose sum is σ = 21012308. Its totient is φ = 21012306.

The previous prime is 21012301. The next prime is 21012311. The reversal of 21012307 is 70321012.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21012307 - 2¹¹ = 21010259 is a prime.

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

It is not a weakly prime, because it can be changed into another prime (21012301) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10506153 + 10506154.

It is an arithmetic number, because the mean of its divisors is an integer number (10506154).

Almost surely, 2^21012307 is an apocalyptic number.

21012307 is a deficient number, since it is larger than the sum of its proper divisors (1).

21012307 is an equidigital number, since it uses as much as digits as its factorization.

21012307 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 84, while the sum is 16.

The square root of 21012307 is about 4583.9183020643. The cubic root of 21012307 is about 275.9463024779.

Adding to 21012307 its reverse (70321012), we get a palindrome (91333319).

The spelling of 21012307 in words is "twenty-one million, twelve thousand, three hundred seven".