21156104545 has 4 divisors (see below), whose sum is σ = 25387325460. Its totient is φ = 16924883632.

The previous prime is 21156104539. The next prime is 21156104551. The reversal of 21156104545 is 54540165112.

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

It is an interprime number because it is at equal distance from previous prime (21156104539) and next prime (21156104551).

It can be written as a sum of positive squares in 2 ways, for example, as 13621690944 + 7534413601 = 116712^2 + 86801^2 .

It is a cyclic number.

It is not a de Polignac number, because 21156104545 - 2¹¹ = 21156102497 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21156104545.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2115610450 + ... + 2115610459.

It is an arithmetic number, because the mean of its divisors is an integer number (6346831365).

Almost surely, 2^21156104545 is an apocalyptic number.

It is an amenable number.

21156104545 is a deficient number, since it is larger than the sum of its proper divisors (4231220915).

21156104545 is an equidigital number, since it uses as much as digits as its factorization.

21156104545 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4231220914.

The product of its (nonzero) digits is 24000, while the sum is 34.

Adding to 21156104545 its reverse (54540165112), we get a palindrome (75696269657).

The spelling of 21156104545 in words is "twenty-one billion, one hundred fifty-six million, one hundred four thousand, five hundred forty-five".