21956069 has 2 divisors, whose sum is σ = 21956070. Its totient is φ = 21956068.

The previous prime is 21956041. The next prime is 21956089. The reversal of 21956069 is 96065912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12159169 + 9796900 = 3487^2 + 3130^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21956069 is a prime.

It is a super-2 number, since 2×21956069² = 964137931865522, which contains 22 as substring.

It is a Chen prime.

It is equal to p_1386677 and since 21956069 and 1386677 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21956009) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10978034 + 10978035.

It is an arithmetic number, because the mean of its divisors is an integer number (10978035).

Almost surely, 2^21956069 is an apocalyptic number.

It is an amenable number.

21956069 is a deficient number, since it is larger than the sum of its proper divisors (1).

21956069 is an equidigital number, since it uses as much as digits as its factorization.

21956069 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 29160, while the sum is 38.

The square root of 21956069 is about 4685.7303592930. The cubic root of 21956069 is about 280.0172991013.

The spelling of 21956069 in words is "twenty-one million, nine hundred fifty-six thousand, sixty-nine".