21716869 has 2 divisors, whose sum is σ = 21716870. Its totient is φ = 21716868.

The previous prime is 21716861. The next prime is 21716881. The reversal of 21716869 is 96861712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14630625 + 7086244 = 3825^2 + 2662^2 .

It is a cyclic number.

It is not a de Polignac number, because 21716869 - 2³ = 21716861 is a prime.

It is a super-2 number, since 2×21716869² = 943244798326322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21716861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10858434 + 10858435.

It is an arithmetic number, because the mean of its divisors is an integer number (10858435).

Almost surely, 2^21716869 is an apocalyptic number.

It is an amenable number.

21716869 is a deficient number, since it is larger than the sum of its proper divisors (1).

21716869 is an equidigital number, since it uses as much as digits as its factorization.

21716869 is an evil number, because the sum of its binary digits is even.

The product of its digits is 36288, while the sum is 40.

The square root of 21716869 is about 4660.1361568092. The cubic root of 21716869 is about 278.9967026413.

The spelling of 21716869 in words is "twenty-one million, seven hundred sixteen thousand, eight hundred sixty-nine".