20723740591649 has 2 divisors, whose sum is σ = 20723740591650. Its totient is φ = 20723740591648.

The previous prime is 20723740591613. The next prime is 20723740591691. The reversal of 20723740591649 is 94619504732702.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19541421442624 + 1182319149025 = 4420568^2 + 1087345^2 .

It is a cyclic number.

It is not a de Polignac number, because 20723740591649 - 2²⁸ = 20723472156193 is a prime.

It is not a weakly prime, because it can be changed into another prime (20723740531649) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10361870295824 + 10361870295825.

It is an arithmetic number, because the mean of its divisors is an integer number (10361870295825).

Almost surely, 2^{20723740591649} is an apocalyptic number.

It is an amenable number.

20723740591649 is a deficient number, since it is larger than the sum of its proper divisors (1).

20723740591649 is an equidigital number, since it uses as much as digits as its factorization.

20723740591649 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 22861440, while the sum is 59.

The spelling of 20723740591649 in words is "twenty trillion, seven hundred twenty-three billion, seven hundred forty million, five hundred ninety-one thousand, six hundred forty-nine".