21644153233 has 2 divisors, whose sum is σ = 21644153234. Its totient is φ = 21644153232.

The previous prime is 21644153191. The next prime is 21644153239. The reversal of 21644153233 is 33235144612.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18705212289 + 2938940944 = 136767^2 + 54212^2 .

It is a cyclic number.

It is not a de Polignac number, because 21644153233 - 2¹⁷ = 21644022161 is a prime.

It is not a weakly prime, because it can be changed into another prime (21644153239) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10822076616 + 10822076617.

It is an arithmetic number, because the mean of its divisors is an integer number (10822076617).

Almost surely, 2^21644153233 is an apocalyptic number.

It is an amenable number.

21644153233 is a deficient number, since it is larger than the sum of its proper divisors (1).

21644153233 is an equidigital number, since it uses as much as digits as its factorization.

21644153233 is an evil number, because the sum of its binary digits is even.

The product of its digits is 51840, while the sum is 34.

Adding to 21644153233 its reverse (33235144612), we get a palindrome (54879297845).

The spelling of 21644153233 in words is "twenty-one billion, six hundred forty-four million, one hundred fifty-three thousand, two hundred thirty-three".