21765769 has 2 divisors, whose sum is σ = 21765770. Its totient is φ = 21765768.

The previous prime is 21765761. The next prime is 21765839. The reversal of 21765769 is 96756712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13286025 + 8479744 = 3645^2 + 2912^2 .

It is a cyclic number.

It is not a de Polignac number, because 21765769 - 2³ = 21765761 is a prime.

It is a super-2 number, since 2×21765769² = 947497400322722, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21765761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10882884 + 10882885.

It is an arithmetic number, because the mean of its divisors is an integer number (10882885).

Almost surely, 2^21765769 is an apocalyptic number.

It is an amenable number.

21765769 is a deficient number, since it is larger than the sum of its proper divisors (1).

21765769 is an equidigital number, since it uses as much as digits as its factorization.

21765769 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 158760, while the sum is 43.

The square root of 21765769 is about 4665.3798344829. The cubic root of 21765769 is about 279.2059518289.

The spelling of 21765769 in words is "twenty-one million, seven hundred sixty-five thousand, seven hundred sixty-nine".