21065117771 has 8 divisors (see below), whose sum is σ = 22178080320. Its totient is φ = 19952582472.

The previous prime is 21065117767. The next prime is 21065117791. The reversal of 21065117771 is 17771156012.

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 21065117771 - 2² = 21065117767 is a prime.

It is a super-2 number, since 2×21065117771² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21065117791) 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, 3005 + ... + 205278.

It is an arithmetic number, because the mean of its divisors is an integer number (2772260040).

Almost surely, 2^21065117771 is an apocalyptic number.

21065117771 is a deficient number, since it is larger than the sum of its proper divisors (1112962549).

21065117771 is a wasteful number, since it uses less digits than its factorization.

21065117771 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 213625.

The product of its (nonzero) digits is 20580, while the sum is 38.

The spelling of 21065117771 in words is "twenty-one billion, sixty-five million, one hundred seventeen thousand, seven hundred seventy-one".