21697034561 has 2 divisors, whose sum is σ = 21697034562. Its totient is φ = 21697034560.

The previous prime is 21697034531. The next prime is 21697034663. The reversal of 21697034561 is 16543079612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20403265600 + 1293768961 = 142840^2 + 35969^2 .

It is a cyclic number.

It is not a de Polignac number, because 21697034561 - 2⁶ = 21697034497 is a prime.

It is a super-2 number, since 2×21697034561² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21697034531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10848517280 + 10848517281.

It is an arithmetic number, because the mean of its divisors is an integer number (10848517281).

Almost surely, 2^21697034561 is an apocalyptic number.

It is an amenable number.

21697034561 is a deficient number, since it is larger than the sum of its proper divisors (1).

21697034561 is an equidigital number, since it uses as much as digits as its factorization.

21697034561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 272160, while the sum is 44.

The spelling of 21697034561 in words is "twenty-one billion, six hundred ninety-seven million, thirty-four thousand, five hundred sixty-one".