21799553 has 2 divisors, whose sum is σ = 21799554. Its totient is φ = 21799552.

The previous prime is 21799529. The next prime is 21799567. The reversal of 21799553 is 35599712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21003889 + 795664 = 4583^2 + 892^2 .

It is a cyclic number.

It is not a de Polignac number, because 21799553 - 2¹² = 21795457 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21799553.

It is not a weakly prime, because it can be changed into another prime (21799513) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10899776 + 10899777.

It is an arithmetic number, because the mean of its divisors is an integer number (10899777).

Almost surely, 2^21799553 is an apocalyptic number.

It is an amenable number.

21799553 is a deficient number, since it is larger than the sum of its proper divisors (1).

21799553 is an equidigital number, since it uses as much as digits as its factorization.

21799553 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 85050, while the sum is 41.

The square root of 21799553 is about 4668.9991432854. Note that the first 3 decimals coincide. The cubic root of 21799553 is about 279.3503347776.

The spelling of 21799553 in words is "twenty-one million, seven hundred ninety-nine thousand, five hundred fifty-three".