21266513 has 16 divisors (see below), whose sum is σ = 23003136. Its totient is φ = 19612560.

The previous prime is 21266503. The next prime is 21266519. The reversal of 21266513 is 31566212.

It is not a de Polignac number, because 21266513 - 2⁶ = 21266449 is a prime.

It is a Duffinian number.

It is a zygodrome in base 3.

It is not an unprimeable number, because it can be changed into a prime (21266519) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 111248 + ... + 111438.

It is an arithmetic number, because the mean of its divisors is an integer number (1437696).

Almost surely, 2^21266513 is an apocalyptic number.

21266513 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21266513 is a deficient number, since it is larger than the sum of its proper divisors (1736623).

21266513 is a wasteful number, since it uses less digits than its factorization.

21266513 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 364.

The product of its digits is 2160, while the sum is 26.

The square root of 21266513 is about 4611.5629671512. The cubic root of 21266513 is about 277.0546404394.

The spelling of 21266513 in words is "twenty-one million, two hundred sixty-six thousand, five hundred thirteen".