21235737109 has 2 divisors, whose sum is σ = 21235737110. Its totient is φ = 21235737108.

The previous prime is 21235737077. The next prime is 21235737161. The reversal of 21235737109 is 90173753212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15132690225 + 6103046884 = 123015^2 + 78122^2 .

It is a cyclic number.

It is not a de Polignac number, because 21235737109 - 2⁵ = 21235737077 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21235731109) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10617868554 + 10617868555.

It is an arithmetic number, because the mean of its divisors is an integer number (10617868555).

Almost surely, 2^21235737109 is an apocalyptic number.

It is an amenable number.

21235737109 is a deficient number, since it is larger than the sum of its proper divisors (1).

21235737109 is an equidigital number, since it uses as much as digits as its factorization.

21235737109 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 79380, while the sum is 40.

The spelling of 21235737109 in words is "twenty-one billion, two hundred thirty-five million, seven hundred thirty-seven thousand, one hundred nine".