21151443442993 has 4 divisors (see below), whose sum is σ = 21369499561060. Its totient is φ = 20933387324928.

The previous prime is 21151443442979. The next prime is 21151443443021. The reversal of 21151443442993 is 39924434415112.

It is a happy number.

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 10459642134769 + 10691801308224 = 3234137^2 + 3269832^2 .

It is a cyclic number.

It is not a de Polignac number, because 21151443442993 - 2³³ = 21142853508401 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 21151443442993.

It is not an unprimeable number, because it can be changed into a prime (21151443442093) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 109028058888 + ... + 109028059081.

It is an arithmetic number, because the mean of its divisors is an integer number (5342374890265).

Almost surely, 2^{21151443442993} is an apocalyptic number.

It is an amenable number.

21151443442993 is a deficient number, since it is larger than the sum of its proper divisors (218056118067).

21151443442993 is an equidigital number, since it uses as much as digits as its factorization.

21151443442993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 218056118066.

The product of its digits is 3732480, while the sum is 52.

The spelling of 21151443442993 in words is "twenty-one trillion, one hundred fifty-one billion, four hundred forty-three million, four hundred forty-two thousand, nine hundred ninety-three".