21111585749 has 2 divisors, whose sum is σ = 21111585750. Its totient is φ = 21111585748.

The previous prime is 21111585697. The next prime is 21111585787. The reversal of 21111585749 is 94758511112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17744104849 + 3367480900 = 133207^2 + 58030^2 .

It is a cyclic number.

It is not a de Polignac number, because 21111585749 - 2⁸ = 21111585493 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21111585049) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10555792874 + 10555792875.

It is an arithmetic number, because the mean of its divisors is an integer number (10555792875).

Almost surely, 2^21111585749 is an apocalyptic number.

It is an amenable number.

21111585749 is a deficient number, since it is larger than the sum of its proper divisors (1).

21111585749 is an equidigital number, since it uses as much as digits as its factorization.

21111585749 is an evil number, because the sum of its binary digits is even.

The product of its digits is 100800, while the sum is 44.

The spelling of 21111585749 in words is "twenty-one billion, one hundred eleven million, five hundred eighty-five thousand, seven hundred forty-nine".