21718211606 has 64 divisors (see below), whose sum is σ = 40606798848. Its totient is φ = 8482900608.

The previous prime is 21718211533. The next prime is 21718211617. The reversal of 21718211606 is 60611281712.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4655231 + ... + 4659893.

It is an arithmetic number, because the mean of its divisors is an integer number (634481232).

Almost surely, 2^21718211606 is an apocalyptic number.

21718211606 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21718211606 is a deficient number, since it is larger than the sum of its proper divisors (18888587242).

21718211606 is a wasteful number, since it uses less digits than its factorization.

21718211606 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5005.

The product of its (nonzero) digits is 8064, while the sum is 35.

Adding to 21718211606 its sum of digits (35), we get a square (21718211641 = 147371²).

The spelling of 21718211606 in words is "twenty-one billion, seven hundred eighteen million, two hundred eleven thousand, six hundred six".