21709642069 has 2 divisors, whose sum is σ = 21709642070. Its totient is φ = 21709642068.

The previous prime is 21709642037. The next prime is 21709642091. The reversal of 21709642069 is 96024690712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19741655025 + 1967987044 = 140505^2 + 44362^2 .

It is a cyclic number.

It is not a de Polignac number, because 21709642069 - 2⁵ = 21709642037 is a prime.

It is a super-2 number, since 2×21709642069² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21709642169) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10854821034 + 10854821035.

It is an arithmetic number, because the mean of its divisors is an integer number (10854821035).

Almost surely, 2^21709642069 is an apocalyptic number.

It is an amenable number.

21709642069 is a deficient number, since it is larger than the sum of its proper divisors (1).

21709642069 is an equidigital number, since it uses as much as digits as its factorization.

21709642069 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 326592, while the sum is 46.

The spelling of 21709642069 in words is "twenty-one billion, seven hundred nine million, six hundred forty-two thousand, sixty-nine".