21368777 has 2 divisors, whose sum is σ = 21368778. Its totient is φ = 21368776.

The previous prime is 21368761. The next prime is 21368791. The reversal of 21368777 is 77786312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11262736 + 10106041 = 3356^2 + 3179^2 .

It is a cyclic number.

It is not a de Polignac number, because 21368777 - 2⁴ = 21368761 is a prime.

It is not a weakly prime, because it can be changed into another prime (21368707) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10684388 + 10684389.

It is an arithmetic number, because the mean of its divisors is an integer number (10684389).

Almost surely, 2^21368777 is an apocalyptic number.

It is an amenable number.

21368777 is a deficient number, since it is larger than the sum of its proper divisors (1).

21368777 is an equidigital number, since it uses as much as digits as its factorization.

21368777 is an evil number, because the sum of its binary digits is even.

The product of its digits is 98784, while the sum is 41.

The square root of 21368777 is about 4622.6374506336. The cubic root of 21368777 is about 277.4980201682.

The spelling of 21368777 in words is "twenty-one million, three hundred sixty-eight thousand, seven hundred seventy-seven".