21025507 has 2 divisors, whose sum is σ = 21025508. Its totient is φ = 21025506.

The previous prime is 21025469. The next prime is 21025513. The reversal of 21025507 is 70552012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21025507 - 2¹¹ = 21023459 is a prime.

It is not a weakly prime, because it can be changed into another prime (21025307) 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 as a sum of consecutive naturals, namely, 10512753 + 10512754.

It is an arithmetic number, because the mean of its divisors is an integer number (10512754).

Almost surely, 2^21025507 is an apocalyptic number.

21025507 is a deficient number, since it is larger than the sum of its proper divisors (1).

21025507 is an equidigital number, since it uses as much as digits as its factorization.

21025507 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 700, while the sum is 22.

The square root of 21025507 is about 4585.3578922479. The cubic root of 21025507 is about 276.0040738389.

Adding to 21025507 its reverse (70552012), we get a palindrome (91577519).

The spelling of 21025507 in words is "twenty-one million, twenty-five thousand, five hundred seven".