21163696777 has 6 divisors (see below), whose sum is σ = 21383326874. Its totient is φ = 20944096320.

The previous prime is 21163696769. The next prime is 21163696783. The reversal of 21163696777 is 77769636112.

It can be written as a sum of positive squares in only one way, i.e., 17672777721 + 3490919056 = 132939^2 + 59084^2 .

It is not a de Polignac number, because 21163696777 - 2³ = 21163696769 is a prime.

It is a super-2 number, since 2×21163696777² (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 (21163690777) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1425402 + ... + 1440172.

Almost surely, 2^21163696777 is an apocalyptic number.

It is an amenable number.

21163696777 is a deficient number, since it is larger than the sum of its proper divisors (219630097).

21163696777 is an frugal number, since it uses more digits than its factorization.

21163696777 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29639 (or 14868 counting only the distinct ones).

The product of its digits is 4000752, while the sum is 55.

The spelling of 21163696777 in words is "twenty-one billion, one hundred sixty-three million, six hundred ninety-six thousand, seven hundred seventy-seven".