21025042145 has 16 divisors (see below), whose sum is σ = 26728088400. Its totient is φ = 15822372864.

The previous prime is 21025042123. The next prime is 21025042153. The reversal of 21025042145 is 54124052012.

It can be written as a sum of positive squares in 8 ways, for example, as 4806510241 + 16218531904 = 69329^2 + 127352^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21025042145 is a prime.

It is an unprimeable number.

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 in 15 ways as a sum of consecutive naturals, for example, 102209 + ... + 229121.

It is an arithmetic number, because the mean of its divisors is an integer number (1670505525).

Almost surely, 2^21025042145 is an apocalyptic number.

It is an amenable number.

21025042145 is a deficient number, since it is larger than the sum of its proper divisors (5703046255).

21025042145 is a wasteful number, since it uses less digits than its factorization.

21025042145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128884.

The product of its (nonzero) digits is 3200, while the sum is 26.

Adding to 21025042145 its reverse (54124052012), we get a palindrome (75149094157).

The spelling of 21025042145 in words is "twenty-one billion, twenty-five million, forty-two thousand, one hundred forty-five".