21423721306 has 16 divisors (see below), whose sum is σ = 35174889288. Its totient is φ = 9725774400.

The previous prime is 21423721259. The next prime is 21423721331. The reversal of 21423721306 is 60312732412.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 14542189281 + 6881532025 = 120591^2 + 82955^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6752425 + ... + 6755596.

Almost surely, 2^21423721306 is an apocalyptic number.

21423721306 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21423721306 is a deficient number, since it is larger than the sum of its proper divisors (13751167982).

21423721306 is a wasteful number, since it uses less digits than its factorization.

21423721306 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13508097.

The product of its (nonzero) digits is 12096, while the sum is 31.

The spelling of 21423721306 in words is "twenty-one billion, four hundred twenty-three million, seven hundred twenty-one thousand, three hundred six".