21268777 has 2 divisors, whose sum is σ = 21268778. Its totient is φ = 21268776.

The previous prime is 21268763. The next prime is 21268787. The reversal of 21268777 is 77786212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14409616 + 6859161 = 3796^2 + 2619^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21268777 is a prime.

It is not a weakly prime, because it can be changed into another prime (21268727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10634388 + 10634389.

It is an arithmetic number, because the mean of its divisors is an integer number (10634389).

Almost surely, 2^21268777 is an apocalyptic number.

It is an amenable number.

21268777 is a deficient number, since it is larger than the sum of its proper divisors (1).

21268777 is an equidigital number, since it uses as much as digits as its factorization.

21268777 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 65856, while the sum is 40.

The square root of 21268777 is about 4611.8084305400. The cubic root of 21268777 is about 277.0644716930.

The spelling of 21268777 in words is "twenty-one million, two hundred sixty-eight thousand, seven hundred seventy-seven".