21726820306 has 4 divisors (see below), whose sum is σ = 32590230462. Its totient is φ = 10863410152.

The previous prime is 21726820289. The next prime is 21726820307. The reversal of 21726820306 is 60302862712.

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

It can be written as a sum of positive squares in only one way, i.e., 18293915025 + 3432905281 = 135255^2 + 58591^2 .

It is not an unprimeable number, because it can be changed into a prime (21726820307) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5431705075 + ... + 5431705078.

Almost surely, 2^21726820306 is an apocalyptic number.

21726820306 is a deficient number, since it is larger than the sum of its proper divisors (10863410156).

21726820306 is a wasteful number, since it uses less digits than its factorization.

21726820306 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10863410155.

The product of its (nonzero) digits is 48384, while the sum is 37.

The spelling of 21726820306 in words is "twenty-one billion, seven hundred twenty-six million, eight hundred twenty thousand, three hundred six".