21205303144 has 8 divisors (see below), whose sum is σ = 39759943410. Its totient is φ = 10602651568.

The previous prime is 21205303129. The next prime is 21205303159. The reversal of 21205303144 is 44130350212.

It is an interprime number because it is at equal distance from previous prime (21205303129) and next prime (21205303159).

It can be written as a sum of positive squares in only one way, i.e., 16355852100 + 4849451044 = 127890^2 + 69638^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1325331439 + ... + 1325331454.

Almost surely, 2^21205303144 is an apocalyptic number.

It is an amenable number.

21205303144 is a deficient number, since it is larger than the sum of its proper divisors (18554640266).

21205303144 is a wasteful number, since it uses less digits than its factorization.

21205303144 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2650662899 (or 2650662895 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 25.

Adding to 21205303144 its reverse (44130350212), we get a palindrome (65335653356).

The spelling of 21205303144 in words is "twenty-one billion, two hundred five million, three hundred three thousand, one hundred forty-four".