21170399640889 has 2 divisors, whose sum is σ = 21170399640890. Its totient is φ = 21170399640888.

The previous prime is 21170399640829. The next prime is 21170399640913. The reversal of 21170399640889 is 98804699307112.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19452360293289 + 1718039347600 = 4410483^2 + 1310740^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21170399640889 is a prime.

It is not a weakly prime, because it can be changed into another prime (21170399640809) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10585199820444 + 10585199820445.

It is an arithmetic number, because the mean of its divisors is an integer number (10585199820445).

Almost surely, 2^{21170399640889} is an apocalyptic number.

It is an amenable number.

21170399640889 is a deficient number, since it is larger than the sum of its proper divisors (1).

21170399640889 is an equidigital number, since it uses as much as digits as its factorization.

21170399640889 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 47029248, while the sum is 67.

The spelling of 21170399640889 in words is "twenty-one trillion, one hundred seventy billion, three hundred ninety-nine million, six hundred forty thousand, eight hundred eighty-nine".