21727397 has 2 divisors, whose sum is σ = 21727398. Its totient is φ = 21727396.

The previous prime is 21727369. The next prime is 21727429. The reversal of 21727397 is 79372712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20349121 + 1378276 = 4511^2 + 1174^2 .

It is a cyclic number.

It is not a de Polignac number, because 21727397 - 2⁶ = 21727333 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21727397.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21727337) 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, 10863698 + 10863699.

It is an arithmetic number, because the mean of its divisors is an integer number (10863699).

Almost surely, 2^21727397 is an apocalyptic number.

It is an amenable number.

21727397 is a deficient number, since it is larger than the sum of its proper divisors (1).

21727397 is an equidigital number, since it uses as much as digits as its factorization.

21727397 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 37044, while the sum is 38.

The square root of 21727397 is about 4661.2656006711. The cubic root of 21727397 is about 279.0417797772.

The spelling of 21727397 in words is "twenty-one million, seven hundred twenty-seven thousand, three hundred ninety-seven".