21712771 has 4 divisors (see below), whose sum is σ = 21936712. Its totient is φ = 21488832.

The previous prime is 21712753. The next prime is 21712781. The reversal of 21712771 is 17721712.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21712771 - 2⁷ = 21712643 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21712781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 111825 + ... + 112018.

It is an arithmetic number, because the mean of its divisors is an integer number (5484178).

Almost surely, 2^21712771 is an apocalyptic number.

21712771 is a deficient number, since it is larger than the sum of its proper divisors (223941).

21712771 is an equidigital number, since it uses as much as digits as its factorization.

21712771 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 223940.

The product of its digits is 1372, while the sum is 28.

The square root of 21712771 is about 4659.6964493409. The cubic root of 21712771 is about 278.9791525299.

The spelling of 21712771 in words is "twenty-one million, seven hundred twelve thousand, seven hundred seventy-one".