21171771 has 12 divisors (see below), whose sum is σ = 30624048. Its totient is φ = 14094864.

The previous prime is 21171767. The next prime is 21171779. The reversal of 21171771 is 17717112.

It is not a de Polignac number, because 21171771 - 2² = 21171767 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21171779) 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, 8461 + ... + 10673.

It is an arithmetic number, because the mean of its divisors is an integer number (2552004).

Almost surely, 2^21171771 is an apocalyptic number.

21171771 is a deficient number, since it is larger than the sum of its proper divisors (9452277).

21171771 is a wasteful number, since it uses less digits than its factorization.

21171771 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3282 (or 3279 counting only the distinct ones).

The product of its digits is 686, while the sum is 27.

The square root of 21171771 is about 4601.2792786355. The cubic root of 21171771 is about 276.6426031877.

Adding to 21171771 its reverse (17717112), we get a palindrome (38888883).

The spelling of 21171771 in words is "twenty-one million, one hundred seventy-one thousand, seven hundred seventy-one".