20561164302661 has 8 divisors (see below), whose sum is σ = 21411032025600. Its totient is φ = 19720687383600.

The previous prime is 20561164302647. The next prime is 20561164302697. The reversal of 20561164302661 is 16620346116502.

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 20561164302661 - 2⁷ = 20561164302533 is a prime.

It is a super-2 number, since 2×20561164302661² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20561164302641) 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, 2347696501 + ... + 2347705258.

It is an arithmetic number, because the mean of its divisors is an integer number (2676379003200).

Almost surely, 2^{20561164302661} is an apocalyptic number.

It is an amenable number.

20561164302661 is a deficient number, since it is larger than the sum of its proper divisors (849867722939).

20561164302661 is a wasteful number, since it uses less digits than its factorization.

20561164302661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4695401939.

The product of its (nonzero) digits is 311040, while the sum is 43.

The spelling of 20561164302661 in words is "twenty trillion, five hundred sixty-one billion, one hundred sixty-four million, three hundred two thousand, six hundred sixty-one".