21675553 has 2 divisors, whose sum is σ = 21675554. Its totient is φ = 21675552.

The previous prime is 21675529. The next prime is 21675559. The reversal of 21675553 is 35557612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12723489 + 8952064 = 3567^2 + 2992^2 .

It is a cyclic number.

It is not a de Polignac number, because 21675553 - 2⁹ = 21675041 is a prime.

It is not a weakly prime, because it can be changed into another prime (21675559) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10837776 + 10837777.

It is an arithmetic number, because the mean of its divisors is an integer number (10837777).

Almost surely, 2^21675553 is an apocalyptic number.

It is an amenable number.

21675553 is a deficient number, since it is larger than the sum of its proper divisors (1).

21675553 is an equidigital number, since it uses as much as digits as its factorization.

21675553 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31500, while the sum is 34.

The square root of 21675553 is about 4655.7011287238. The cubic root of 21675553 is about 278.8196613821.

The spelling of 21675553 in words is "twenty-one million, six hundred seventy-five thousand, five hundred fifty-three".