21311240233 has 2 divisors, whose sum is σ = 21311240234. Its totient is φ = 21311240232.

The previous prime is 21311240201. The next prime is 21311240261. The reversal of 21311240233 is 33204211312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19232974489 + 2078265744 = 138683^2 + 45588^2 .

It is a cyclic number.

It is not a de Polignac number, because 21311240233 - 2⁵ = 21311240201 is a prime.

It is not a weakly prime, because it can be changed into another prime (21311240263) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10655620116 + 10655620117.

It is an arithmetic number, because the mean of its divisors is an integer number (10655620117).

Almost surely, 2^21311240233 is an apocalyptic number.

It is an amenable number.

21311240233 is a deficient number, since it is larger than the sum of its proper divisors (1).

21311240233 is an equidigital number, since it uses as much as digits as its factorization.

21311240233 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864, while the sum is 22.

Adding to 21311240233 its reverse (33204211312), we get a palindrome (54515451545).

The spelling of 21311240233 in words is "twenty-one billion, three hundred eleven million, two hundred forty thousand, two hundred thirty-three".