21772717 has 4 divisors (see below), whose sum is σ = 21997276. Its totient is φ = 21548160.

The previous prime is 21772691. The next prime is 21772741. The reversal of 21772717 is 71727712.

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

It can be written as a sum of positive squares in 2 ways, for example, as 5924356 + 15848361 = 2434^2 + 3981^2 .

It is a cyclic number.

It is not a de Polignac number, because 21772717 - 2⁷ = 21772589 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21772787) 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, 112134 + ... + 112327.

It is an arithmetic number, because the mean of its divisors is an integer number (5499319).

Almost surely, 2^21772717 is an apocalyptic number.

It is an amenable number.

21772717 is a deficient number, since it is larger than the sum of its proper divisors (224559).

21772717 is an equidigital number, since it uses as much as digits as its factorization.

21772717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 224558.

The product of its digits is 9604, while the sum is 34.

The square root of 21772717 is about 4666.1244089715. The cubic root of 21772717 is about 279.2356577488.

The spelling of 21772717 in words is "twenty-one million, seven hundred seventy-two thousand, seven hundred seventeen".