21557224453 has 2 divisors, whose sum is σ = 21557224454. Its totient is φ = 21557224452.

The previous prime is 21557224427. The next prime is 21557224517. The reversal of 21557224453 is 35442275512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17924389924 + 3632834529 = 133882^2 + 60273^2 .

It is a cyclic number.

It is not a de Polignac number, because 21557224453 - 2¹⁷ = 21557093381 is a prime.

It is a super-2 number, since 2×21557224453² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21557024453) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10778612226 + 10778612227.

It is an arithmetic number, because the mean of its divisors is an integer number (10778612227).

Almost surely, 2^21557224453 is an apocalyptic number.

It is an amenable number.

21557224453 is a deficient number, since it is larger than the sum of its proper divisors (1).

21557224453 is an equidigital number, since it uses as much as digits as its factorization.

21557224453 is an evil number, because the sum of its binary digits is even.

The product of its digits is 336000, while the sum is 40.

Adding to 21557224453 its reverse (35442275512), we get a palindrome (56999499965).

The spelling of 21557224453 in words is "twenty-one billion, five hundred fifty-seven million, two hundred twenty-four thousand, four hundred fifty-three".