21571009806 has 32 divisors (see below), whose sum is σ = 44606112768. Its totient is φ = 6947075520.

The previous prime is 21571009787. The next prime is 21571009841. The reversal of 21571009806 is 60890017512.

It is a congruent number.

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 15 ways as a sum of consecutive naturals, for example, 20781 + ... + 208743.

It is an arithmetic number, because the mean of its divisors is an integer number (1393941024).

Almost surely, 2^21571009806 is an apocalyptic number.

21571009806 is an abundant number, since it is smaller than the sum of its proper divisors (23035102962).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21571009806 is a wasteful number, since it uses less digits than its factorization.

21571009806 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 188616.

The product of its (nonzero) digits is 30240, while the sum is 39.

The spelling of 21571009806 in words is "twenty-one billion, five hundred seventy-one million, nine thousand, eight hundred six".