21553459 has 2 divisors, whose sum is σ = 21553460. Its totient is φ = 21553458.

The previous prime is 21553453. The next prime is 21553481. The reversal of 21553459 is 95435512.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21553459 is a prime.

It is not a weakly prime, because it can be changed into another prime (21553453) 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, 10776729 + 10776730.

It is an arithmetic number, because the mean of its divisors is an integer number (10776730).

Almost surely, 2^21553459 is an apocalyptic number.

21553459 is a deficient number, since it is larger than the sum of its proper divisors (1).

21553459 is an equidigital number, since it uses as much as digits as its factorization.

21553459 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 27000, while the sum is 34.

The square root of 21553459 is about 4642.5703010294. The cubic root of 21553459 is about 278.2951637890.

The spelling of 21553459 in words is "twenty-one million, five hundred fifty-three thousand, four hundred fifty-nine".