21309107 has 2 divisors, whose sum is σ = 21309108. Its totient is φ = 21309106.

The previous prime is 21309103. The next prime is 21309133. The reversal of 21309107 is 70190312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21309107 - 2² = 21309103 is a prime.

It is a super-2 number, since 2×21309107² = 908156082274898, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21309103) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10654553 + 10654554.

It is an arithmetic number, because the mean of its divisors is an integer number (10654554).

Almost surely, 2^21309107 is an apocalyptic number.

21309107 is a deficient number, since it is larger than the sum of its proper divisors (1).

21309107 is an equidigital number, since it uses as much as digits as its factorization.

21309107 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 378, while the sum is 23.

The square root of 21309107 is about 4616.1788310246. The cubic root of 21309107 is about 277.2394849661.

Adding to 21309107 its reverse (70190312), we get a palindrome (91499419).

The spelling of 21309107 in words is "twenty-one million, three hundred nine thousand, one hundred seven".