21123307 has 8 divisors (see below), whose sum is σ = 22952960. Its totient is φ = 19365480.

The previous prime is 21123301. The next prime is 21123313. The reversal of 21123307 is 70332112.

It is an interprime number because it is at equal distance from previous prime (21123301) and next prime (21123313).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21123307 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21123301) 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 7 ways as a sum of consecutive naturals, for example, 17343 + ... + 18520.

It is an arithmetic number, because the mean of its divisors is an integer number (2869120).

Almost surely, 2^21123307 is an apocalyptic number.

21123307 is a deficient number, since it is larger than the sum of its proper divisors (1829653).

21123307 is a wasteful number, since it uses less digits than its factorization.

21123307 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35913.

The product of its (nonzero) digits is 252, while the sum is 19.

The square root of 21123307 is about 4596.0098999023. The cubic root of 21123307 is about 276.4313557010.

Adding to 21123307 its reverse (70332112), we get a palindrome (91455419).

The spelling of 21123307 in words is "twenty-one million, one hundred twenty-three thousand, three hundred seven".