21145697689 has 2 divisors, whose sum is σ = 21145697690. Its totient is φ = 21145697688.

The previous prime is 21145697663. The next prime is 21145697693. The reversal of 21145697689 is 98679654112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20704907664 + 440790025 = 143892^2 + 20995^2 .

It is a cyclic number.

It is not a de Polignac number, because 21145697689 - 2¹³ = 21145689497 is a prime.

It is not a weakly prime, because it can be changed into another prime (21145697659) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10572848844 + 10572848845.

It is an arithmetic number, because the mean of its divisors is an integer number (10572848845).

Almost surely, 2^21145697689 is an apocalyptic number.

It is an amenable number.

21145697689 is a deficient number, since it is larger than the sum of its proper divisors (1).

21145697689 is an equidigital number, since it uses as much as digits as its factorization.

21145697689 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6531840, while the sum is 58.

The spelling of 21145697689 in words is "twenty-one billion, one hundred forty-five million, six hundred ninety-seven thousand, six hundred eighty-nine".