21867553 has 2 divisors, whose sum is σ = 21867554. Its totient is φ = 21867552.

The previous prime is 21867551. The next prime is 21867581. The reversal of 21867553 is 35576812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12552849 + 9314704 = 3543^2 + 3052^2 .

It is a cyclic number.

It is not a de Polignac number, because 21867553 - 2¹ = 21867551 is a prime.

Together with 21867551, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21867551) 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, 10933776 + 10933777.

It is an arithmetic number, because the mean of its divisors is an integer number (10933777).

Almost surely, 2^21867553 is an apocalyptic number.

It is an amenable number.

21867553 is a deficient number, since it is larger than the sum of its proper divisors (1).

21867553 is an equidigital number, since it uses as much as digits as its factorization.

21867553 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 50400, while the sum is 37.

The square root of 21867553 is about 4676.2755479120. The cubic root of 21867553 is about 279.6404952457.

The spelling of 21867553 in words is "twenty-one million, eight hundred sixty-seven thousand, five hundred fifty-three".