21701920661 has 8 divisors (see below), whose sum is σ = 21757676160. Its totient is φ = 21646194768.

The previous prime is 21701920657. The next prime is 21701920693. The reversal of 21701920661 is 16602910712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21701920661 - 2² = 21701920657 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21701922661) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2505440 + ... + 2514086.

It is an arithmetic number, because the mean of its divisors is an integer number (2719709520).

Almost surely, 2^21701920661 is an apocalyptic number.

It is an amenable number.

21701920661 is a deficient number, since it is larger than the sum of its proper divisors (55755499).

21701920661 is an equidigital number, since it uses as much as digits as its factorization.

21701920661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14803.

The product of its (nonzero) digits is 9072, while the sum is 35.

The spelling of 21701920661 in words is "twenty-one billion, seven hundred one million, nine hundred twenty thousand, six hundred sixty-one".