21055451 has 2 divisors, whose sum is σ = 21055452. Its totient is φ = 21055450.

The previous prime is 21055429. The next prime is 21055453. The reversal of 21055451 is 15455012.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21055451 - 2⁶ = 21055387 is a prime.

Together with 21055453, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21055453) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10527725 + 10527726.

It is an arithmetic number, because the mean of its divisors is an integer number (10527726).

Almost surely, 2^21055451 is an apocalyptic number.

21055451 is a deficient number, since it is larger than the sum of its proper divisors (1).

21055451 is an equidigital number, since it uses as much as digits as its factorization.

21055451 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1000, while the sum is 23.

The square root of 21055451 is about 4588.6219064116. The cubic root of 21055451 is about 276.1350377144.

The spelling of 21055451 in words is "twenty-one million, fifty-five thousand, four hundred fifty-one".