21771361 has 2 divisors, whose sum is σ = 21771362. Its totient is φ = 21771360.

The previous prime is 21771353. The next prime is 21771367. The reversal of 21771361 is 16317712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21678336 + 93025 = 4656^2 + 305^2 .

It is a cyclic number.

It is not a de Polignac number, because 21771361 - 2³ = 21771353 is a prime.

It is not a weakly prime, because it can be changed into another prime (21771367) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10885680 + 10885681.

It is an arithmetic number, because the mean of its divisors is an integer number (10885681).

Almost surely, 2^21771361 is an apocalyptic number.

It is an amenable number.

21771361 is a deficient number, since it is larger than the sum of its proper divisors (1).

21771361 is an equidigital number, since it uses as much as digits as its factorization.

21771361 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1764, while the sum is 28.

The square root of 21771361 is about 4665.9791041109. The cubic root of 21771361 is about 279.2298607168.

The spelling of 21771361 in words is "twenty-one million, seven hundred seventy-one thousand, three hundred sixty-one".