21155143645145 has 4 divisors (see below), whose sum is σ = 25386172374180. Its totient is φ = 16924114916112.

The previous prime is 21155143645087. The next prime is 21155143645169. The reversal of 21155143645145 is 54154634155112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8691836068864 + 12463307576281 = 2948192^2 + 3530341^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21155143645145 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21155143645145.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2115514364510 + ... + 2115514364519.

It is an arithmetic number, because the mean of its divisors is an integer number (6346543093545).

Almost surely, 2^{21155143645145} is an apocalyptic number.

It is an amenable number.

21155143645145 is a deficient number, since it is larger than the sum of its proper divisors (4231028729035).

21155143645145 is an equidigital number, since it uses as much as digits as its factorization.

21155143645145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4231028729034.

The product of its digits is 1440000, while the sum is 47.

The spelling of 21155143645145 in words is "twenty-one trillion, one hundred fifty-five billion, one hundred forty-three million, six hundred forty-five thousand, one hundred forty-five".