21117356777 has 4 divisors (see below), whose sum is σ = 23037116496. Its totient is φ = 19197597060.

The previous prime is 21117356731. The next prime is 21117356779. The reversal of 21117356777 is 77765371112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21117356777 - 2¹² = 21117352681 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21117356779) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 959879843 + ... + 959879864.

It is an arithmetic number, because the mean of its divisors is an integer number (5759279124).

Almost surely, 2^21117356777 is an apocalyptic number.

It is an amenable number.

21117356777 is a deficient number, since it is larger than the sum of its proper divisors (1919759719).

21117356777 is a wasteful number, since it uses less digits than its factorization.

21117356777 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1919759718.

The product of its digits is 432180, while the sum is 47.

The spelling of 21117356777 in words is "twenty-one billion, one hundred seventeen million, three hundred fifty-six thousand, seven hundred seventy-seven".