21241456561 has 8 divisors (see below), whose sum is σ = 23188777640. Its totient is φ = 19338901632.

The previous prime is 21241456549. The next prime is 21241456597. The reversal of 21241456561 is 16565414212.

It can be written as a sum of positive squares in 4 ways, for example, as 188897536 + 21052559025 = 13744^2 + 145095^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21241456561 - 2¹³ = 21241448369 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21241456561.

It is not an unprimeable number, because it can be changed into a prime (21241454561) 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 7 ways as a sum of consecutive naturals, for example, 11190546 + ... + 11192443.

It is an arithmetic number, because the mean of its divisors is an integer number (2898597205).

Almost surely, 2^21241456561 is an apocalyptic number.

It is an amenable number.

21241456561 is a deficient number, since it is larger than the sum of its proper divisors (1947321079).

21241456561 is a wasteful number, since it uses less digits than its factorization.

21241456561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22383075.

The product of its digits is 57600, while the sum is 37.

The spelling of 21241456561 in words is "twenty-one billion, two hundred forty-one million, four hundred fifty-six thousand, five hundred sixty-one".