21236234477 has 2 divisors, whose sum is σ = 21236234478. Its totient is φ = 21236234476.

The previous prime is 21236234429. The next prime is 21236234483. The reversal of 21236234477 is 77443263212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20162296036 + 1073938441 = 141994^2 + 32771^2 .

It is a cyclic number.

It is not a de Polignac number, because 21236234477 - 2⁶ = 21236234413 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21236231477) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10618117238 + 10618117239.

It is an arithmetic number, because the mean of its divisors is an integer number (10618117239).

Almost surely, 2^21236234477 is an apocalyptic number.

It is an amenable number.

21236234477 is a deficient number, since it is larger than the sum of its proper divisors (1).

21236234477 is an equidigital number, since it uses as much as digits as its factorization.

21236234477 is an evil number, because the sum of its binary digits is even.

The product of its digits is 338688, while the sum is 41.

Adding to 21236234477 its reverse (77443263212), we get a palindrome (98679497689).

The spelling of 21236234477 in words is "twenty-one billion, two hundred thirty-six million, two hundred thirty-four thousand, four hundred seventy-seven".