21155169771 has 12 divisors (see below), whose sum is σ = 30726295600. Its totient is φ = 14025525840.

The previous prime is 21155169757. The next prime is 21155169781. The reversal of 21155169771 is 17796155112.

21155169771 is a `hidden beast` number, since 2 + 1 + 1 + 551 + 6 + 97 + 7 + 1 = 666.

It is not a de Polignac number, because 21155169771 - 2⁷ = 21155169643 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21155169751) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6491671 + ... + 6494928.

Almost surely, 2^21155169771 is an apocalyptic number.

21155169771 is a deficient number, since it is larger than the sum of its proper divisors (9571125829).

21155169771 is a wasteful number, since it uses less digits than its factorization.

21155169771 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12986786 (or 12986783 counting only the distinct ones).

The product of its digits is 132300, while the sum is 45.

The spelling of 21155169771 in words is "twenty-one billion, one hundred fifty-five million, one hundred sixty-nine thousand, seven hundred seventy-one".