21304440406 has 4 divisors (see below), whose sum is σ = 31956660612. Its totient is φ = 10652220202.

The previous prime is 21304440397. The next prime is 21304440473. The reversal of 21304440406 is 60404440312.

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

It is a congruent number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 5326110100 + ... + 5326110103.

It is an arithmetic number, because the mean of its divisors is an integer number (7989165153).

Almost surely, 2^21304440406 is an apocalyptic number.

21304440406 is a deficient number, since it is larger than the sum of its proper divisors (10652220206).

21304440406 is a wasteful number, since it uses less digits than its factorization.

21304440406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10652220205.

The product of its (nonzero) digits is 9216, while the sum is 28.

Adding to 21304440406 its reverse (60404440312), we get a palindrome (81708880718).

The spelling of 21304440406 in words is "twenty-one billion, three hundred four million, four hundred forty thousand, four hundred six".