21113207 has 4 divisors (see below), whose sum is σ = 21267456. Its totient is φ = 20958960.

The previous prime is 21113173. The next prime is 21113221. The reversal of 21113207 is 70231112.

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 21113207 - 2⁸ = 21112951 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21113297) 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, 76919 + ... + 77192.

It is an arithmetic number, because the mean of its divisors is an integer number (5316864).

Almost surely, 2^21113207 is an apocalyptic number.

21113207 is a deficient number, since it is larger than the sum of its proper divisors (154249).

21113207 is a wasteful number, since it uses less digits than its factorization.

21113207 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 154248.

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

The square root of 21113207 is about 4594.9109893446. The cubic root of 21113207 is about 276.3872906028.

Adding to 21113207 its reverse (70231112), we get a palindrome (91344319).

The spelling of 21113207 in words is "twenty-one million, one hundred thirteen thousand, two hundred seven".