21054643 has 2 divisors, whose sum is σ = 21054644. Its totient is φ = 21054642.

The previous prime is 21054617. The next prime is 21054661. The reversal of 21054643 is 34645012.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21054643 is a prime.

It is not a weakly prime, because it can be changed into another prime (21054613) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10527321 + 10527322.

It is an arithmetic number, because the mean of its divisors is an integer number (10527322).

Almost surely, 2^21054643 is an apocalyptic number.

21054643 is a deficient number, since it is larger than the sum of its proper divisors (1).

21054643 is an equidigital number, since it uses as much as digits as its factorization.

21054643 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2880, while the sum is 25.

The square root of 21054643 is about 4588.5338617035. The cubic root of 21054643 is about 276.1315054547.

Adding to 21054643 its reverse (34645012), we get a palindrome (55699655).

The spelling of 21054643 in words is "twenty-one million, fifty-four thousand, six hundred forty-three".