21201553 has 2 divisors, whose sum is σ = 21201554. Its totient is φ = 21201552.

The previous prime is 21201539. The next prime is 21201563. The reversal of 21201553 is 35510212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12837889 + 8363664 = 3583^2 + 2892^2 .

It is a cyclic number.

It is not a de Polignac number, because 21201553 - 2⁹ = 21201041 is a prime.

It is a super-2 number, since 2×21201553² = 899011699223618, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21201553.

It is not a weakly prime, because it can be changed into another prime (21201503) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10600776 + 10600777.

It is an arithmetic number, because the mean of its divisors is an integer number (10600777).

Almost surely, 2^21201553 is an apocalyptic number.

It is an amenable number.

21201553 is a deficient number, since it is larger than the sum of its proper divisors (1).

21201553 is an equidigital number, since it uses as much as digits as its factorization.

21201553 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 300, while the sum is 19.

The square root of 21201553 is about 4604.5144152234. The cubic root of 21201553 is about 276.7722586900.

Adding to 21201553 its reverse (35510212), we get a palindrome (56711765).

The spelling of 21201553 in words is "twenty-one million, two hundred one thousand, five hundred fifty-three".