21690135791 has 2 divisors, whose sum is σ = 21690135792. Its totient is φ = 21690135790.

The previous prime is 21690135781. The next prime is 21690135811. The reversal of 21690135791 is 19753109612.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21690135791 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21690135781) 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, 10845067895 + 10845067896.

It is an arithmetic number, because the mean of its divisors is an integer number (10845067896).

Almost surely, 2^21690135791 is an apocalyptic number.

21690135791 is a deficient number, since it is larger than the sum of its proper divisors (1).

21690135791 is an equidigital number, since it uses as much as digits as its factorization.

21690135791 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 102060, while the sum is 44.

The spelling of 21690135791 in words is "twenty-one billion, six hundred ninety million, one hundred thirty-five thousand, seven hundred ninety-one".