21771539 has 2 divisors, whose sum is σ = 21771540. Its totient is φ = 21771538.

The previous prime is 21771521. The next prime is 21771557. The reversal of 21771539 is 93517712.

It is a happy number.

It is a balanced prime because it is at equal distance from previous prime (21771521) and next prime (21771557).

It is a cyclic number.

It is not a de Polignac number, because 21771539 - 2¹² = 21767443 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21771499 and 21771508.

It is not a weakly prime, because it can be changed into another prime (21771439) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10885769 + 10885770.

It is an arithmetic number, because the mean of its divisors is an integer number (10885770).

Almost surely, 2^21771539 is an apocalyptic number.

21771539 is a deficient number, since it is larger than the sum of its proper divisors (1).

21771539 is an equidigital number, since it uses as much as digits as its factorization.

21771539 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13230, while the sum is 35.

The square root of 21771539 is about 4665.9981783108. The cubic root of 21771539 is about 279.2306216978.

The spelling of 21771539 in words is "twenty-one million, seven hundred seventy-one thousand, five hundred thirty-nine".