21828553 has 2 divisors, whose sum is σ = 21828554. Its totient is φ = 21828552.

The previous prime is 21828551. The next prime is 21828559. The reversal of 21828553 is 35582812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21270544 + 558009 = 4612^2 + 747^2 .

It is a cyclic number.

It is not a de Polignac number, because 21828553 - 2¹ = 21828551 is a prime.

Together with 21828551, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21828551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10914276 + 10914277.

It is an arithmetic number, because the mean of its divisors is an integer number (10914277).

Almost surely, 2^21828553 is an apocalyptic number.

It is an amenable number.

21828553 is a deficient number, since it is larger than the sum of its proper divisors (1).

21828553 is an equidigital number, since it uses as much as digits as its factorization.

21828553 is an evil number, because the sum of its binary digits is even.

The product of its digits is 19200, while the sum is 34.

The square root of 21828553 is about 4672.1037017601. The cubic root of 21828553 is about 279.4741533719.

The spelling of 21828553 in words is "twenty-one million, eight hundred twenty-eight thousand, five hundred fifty-three".