21712106661 has 32 divisors (see below), whose sum is σ = 33446289408. Its totient is φ = 12272195520.

The previous prime is 21712106621. The next prime is 21712106671. The reversal of 21712106661 is 16660121712.

It is not a de Polignac number, because 21712106661 - 2⁹ = 21712106149 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21712106621) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 720466 + ... + 749996.

It is an arithmetic number, because the mean of its divisors is an integer number (1045196544).

Almost surely, 2^21712106661 is an apocalyptic number.

21712106661 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21712106661 is a deficient number, since it is larger than the sum of its proper divisors (11734182747).

21712106661 is a wasteful number, since it uses less digits than its factorization.

21712106661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29921.

The product of its (nonzero) digits is 6048, while the sum is 33.

The spelling of 21712106661 in words is "twenty-one billion, seven hundred twelve million, one hundred six thousand, six hundred sixty-one".