21155211311477 has 2 divisors, whose sum is σ = 21155211311478. Its totient is φ = 21155211311476.

The previous prime is 21155211311441. The next prime is 21155211311489. The reversal of 21155211311477 is 77411311255112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20602212349156 + 552998962321 = 4538966^2 + 743639^2 .

It is a cyclic number.

It is not a de Polignac number, because 21155211311477 - 2¹⁸ = 21155211049333 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21155211311407) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10577605655738 + 10577605655739.

It is an arithmetic number, because the mean of its divisors is an integer number (10577605655739).

Almost surely, 2^{21155211311477} is an apocalyptic number.

It is an amenable number.

21155211311477 is a deficient number, since it is larger than the sum of its proper divisors (1).

21155211311477 is an equidigital number, since it uses as much as digits as its factorization.

21155211311477 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 58800, while the sum is 41.

Adding to 21155211311477 its reverse (77411311255112), we get a palindrome (98566522566589).

The spelling of 21155211311477 in words is "twenty-one trillion, one hundred fifty-five billion, two hundred eleven million, three hundred eleven thousand, four hundred seventy-seven".