21002042961 has 10 divisors (see below), whose sum is σ = 31373422322. Its totient is φ = 14001361920.

The previous prime is 21002042917. The next prime is 21002043017. The reversal of 21002042961 is 16924020012.

21002042961 is a `hidden beast` number, since 210 + 0 + 20 + 429 + 6 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 20777492736 + 224550225 = 144144^2 + 14985^2 .

It is not a de Polignac number, because 21002042961 - 2¹⁰ = 21002041937 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21002042861) 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 in 9 ways as a sum of consecutive naturals, for example, 129642160 + ... + 129642321.

Almost surely, 2^21002042961 is an apocalyptic number.

It is an amenable number.

21002042961 is a deficient number, since it is larger than the sum of its proper divisors (10371379361).

21002042961 is an equidigital number, since it uses as much as digits as its factorization.

21002042961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 259284493 (or 259284484 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

Adding to 21002042961 its reverse (16924020012), we get a palindrome (37926062973).

The spelling of 21002042961 in words is "twenty-one billion, two million, forty-two thousand, nine hundred sixty-one".