20915749 has 2 divisors, whose sum is σ = 20915750. Its totient is φ = 20915748.

The previous prime is 20915743. The next prime is 20915777. The reversal of 20915749 is 94751902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10771524 + 10144225 = 3282^2 + 3185^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20915749 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20915743) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10457874 + 10457875.

It is an arithmetic number, because the mean of its divisors is an integer number (10457875).

Almost surely, 2^20915749 is an apocalyptic number.

It is an amenable number.

20915749 is a deficient number, since it is larger than the sum of its proper divisors (1).

20915749 is an equidigital number, since it uses as much as digits as its factorization.

20915749 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 22680, while the sum is 37.

The square root of 20915749 is about 4573.3739186732. The cubic root of 20915749 is about 275.5229673772.

The spelling of 20915749 in words is "twenty million, nine hundred fifteen thousand, seven hundred forty-nine".