21772742861 has 2 divisors, whose sum is σ = 21772742862. Its totient is φ = 21772742860.

The previous prime is 21772742791. The next prime is 21772742867. The reversal of 21772742861 is 16824727712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21405445636 + 367297225 = 146306^2 + 19165^2 .

It is a cyclic number.

It is not a de Polignac number, because 21772742861 - 2¹⁴ = 21772726477 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21772742867) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10886371430 + 10886371431.

It is an arithmetic number, because the mean of its divisors is an integer number (10886371431).

Almost surely, 2^21772742861 is an apocalyptic number.

It is an amenable number.

21772742861 is a deficient number, since it is larger than the sum of its proper divisors (1).

21772742861 is an equidigital number, since it uses as much as digits as its factorization.

21772742861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 526848, while the sum is 47.

The spelling of 21772742861 in words is "twenty-one billion, seven hundred seventy-two million, seven hundred forty-two thousand, eight hundred sixty-one".