21262643 has 2 divisors, whose sum is σ = 21262644. Its totient is φ = 21262642.

The previous prime is 21262627. The next prime is 21262663. The reversal of 21262643 is 34626212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21262643 - 2⁴ = 21262627 is a prime.

It is not a weakly prime, because it can be changed into another prime (21262663) 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, 10631321 + 10631322.

It is an arithmetic number, because the mean of its divisors is an integer number (10631322).

Almost surely, 2^21262643 is an apocalyptic number.

21262643 is a deficient number, since it is larger than the sum of its proper divisors (1).

21262643 is an equidigital number, since it uses as much as digits as its factorization.

21262643 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3456, while the sum is 26.

The square root of 21262643 is about 4611.1433506236. The cubic root of 21262643 is about 277.0378336329.

Adding to 21262643 its reverse (34626212), we get a palindrome (55888855).

The spelling of 21262643 in words is "twenty-one million, two hundred sixty-two thousand, six hundred forty-three".