21253007 has 2 divisors, whose sum is σ = 21253008. Its totient is φ = 21253006.

The previous prime is 21252997. The next prime is 21253019. The reversal of 21253007 is 70035212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21253007 - 2¹⁸ = 20990863 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21253007.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21250007) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10626503 + 10626504.

It is an arithmetic number, because the mean of its divisors is an integer number (10626504).

Almost surely, 2^21253007 is an apocalyptic number.

21253007 is a deficient number, since it is larger than the sum of its proper divisors (1).

21253007 is an equidigital number, since it uses as much as digits as its factorization.

21253007 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 420, while the sum is 20.

The square root of 21253007 is about 4610.0983720524. The cubic root of 21253007 is about 276.9959771253.

Adding to 21253007 its reverse (70035212), we get a palindrome (91288219).

The spelling of 21253007 in words is "twenty-one million, two hundred fifty-three thousand, seven".