21366561019 has 2 divisors, whose sum is σ = 21366561020. Its totient is φ = 21366561018.

The previous prime is 21366560983. The next prime is 21366561049. The reversal of 21366561019 is 91016566312.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21366561019 - 2⁹ = 21366560507 is a prime.

It is a super-2 number, since 2×21366561019² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21366561049) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10683280509 + 10683280510.

It is an arithmetic number, because the mean of its divisors is an integer number (10683280510).

Almost surely, 2^21366561019 is an apocalyptic number.

21366561019 is a deficient number, since it is larger than the sum of its proper divisors (1).

21366561019 is an equidigital number, since it uses as much as digits as its factorization.

21366561019 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 58320, while the sum is 40.

The spelling of 21366561019 in words is "twenty-one billion, three hundred sixty-six million, five hundred sixty-one thousand, nineteen".