21263507 has 2 divisors, whose sum is σ = 21263508. Its totient is φ = 21263506.

The previous prime is 21263503. The next prime is 21263519. The reversal of 21263507 is 70536212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21263507 - 2² = 21263503 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21263503) 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, 10631753 + 10631754.

It is an arithmetic number, because the mean of its divisors is an integer number (10631754).

Almost surely, 2^21263507 is an apocalyptic number.

21263507 is a deficient number, since it is larger than the sum of its proper divisors (1).

21263507 is an equidigital number, since it uses as much as digits as its factorization.

21263507 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2520, while the sum is 26.

The square root of 21263507 is about 4611.2370357638. The cubic root of 21263507 is about 277.0415860270.

Adding to 21263507 its reverse (70536212), we get a palindrome (91799719).

The spelling of 21263507 in words is "twenty-one million, two hundred sixty-three thousand, five hundred seven".