21361366787 has 2 divisors, whose sum is σ = 21361366788. Its totient is φ = 21361366786.

The previous prime is 21361366751. The next prime is 21361366861. The reversal of 21361366787 is 78766316312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21361366787 - 2¹⁴ = 21361350403 is a prime.

It is not a weakly prime, because it can be changed into another prime (21361366387) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10680683393 + 10680683394.

It is an arithmetic number, because the mean of its divisors is an integer number (10680683394).

Almost surely, 2^21361366787 is an apocalyptic number.

21361366787 is a deficient number, since it is larger than the sum of its proper divisors (1).

21361366787 is an equidigital number, since it uses as much as digits as its factorization.

21361366787 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1524096, while the sum is 50.

The spelling of 21361366787 in words is "twenty-one billion, three hundred sixty-one million, three hundred sixty-six thousand, seven hundred eighty-seven".