21245407 has 2 divisors, whose sum is σ = 21245408. Its totient is φ = 21245406.

The previous prime is 21245387. The next prime is 21245417. The reversal of 21245407 is 70454212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21245407 - 2¹¹ = 21243359 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21245417) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10622703 + 10622704.

It is an arithmetic number, because the mean of its divisors is an integer number (10622704).

Almost surely, 2^21245407 is an apocalyptic number.

21245407 is a deficient number, since it is larger than the sum of its proper divisors (1).

21245407 is an equidigital number, since it uses as much as digits as its factorization.

21245407 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2240, while the sum is 25.

The square root of 21245407 is about 4609.2740209278. The cubic root of 21245407 is about 276.9629555956.

Adding to 21245407 its reverse (70454212), we get a palindrome (91699619).

The spelling of 21245407 in words is "twenty-one million, two hundred forty-five thousand, four hundred seven".