21042307 has 32 divisors (see below), whose sum is σ = 26276544. Its totient is φ = 16588800.

The previous prime is 21042293. The next prime is 21042317. The reversal of 21042307 is 70324012.

It is a cyclic number.

It is not a de Polignac number, because 21042307 - 2¹⁹ = 20518019 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21042317) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 216883 + ... + 216979.

It is an arithmetic number, because the mean of its divisors is an integer number (821142).

Almost surely, 2^21042307 is an apocalyptic number.

21042307 is a deficient number, since it is larger than the sum of its proper divisors (5234237).

21042307 is a wasteful number, since it uses less digits than its factorization.

21042307 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 199.

The product of its (nonzero) digits is 336, while the sum is 19.

The square root of 21042307 is about 4587.1894445292. The cubic root of 21042307 is about 276.0775660658.

Adding to 21042307 its reverse (70324012), we get a palindrome (91366319).

The spelling of 21042307 in words is "twenty-one million, forty-two thousand, three hundred seven".