21025535161 has 2 divisors, whose sum is σ = 21025535162. Its totient is φ = 21025535160.

The previous prime is 21025535107. The next prime is 21025535249. The reversal of 21025535161 is 16153552012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13532901561 + 7492633600 = 116331^2 + 86560^2 .

It is a cyclic number.

It is not a de Polignac number, because 21025535161 - 2¹⁷ = 21025404089 is a prime.

It is not a weakly prime, because it can be changed into another prime (21025545161) 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, 10512767580 + 10512767581.

It is an arithmetic number, because the mean of its divisors is an integer number (10512767581).

Almost surely, 2^21025535161 is an apocalyptic number.

It is an amenable number.

21025535161 is a deficient number, since it is larger than the sum of its proper divisors (1).

21025535161 is an equidigital number, since it uses as much as digits as its factorization.

21025535161 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9000, while the sum is 31.

The spelling of 21025535161 in words is "twenty-one billion, twenty-five million, five hundred thirty-five thousand, one hundred sixty-one".