21328597 has 2 divisors, whose sum is σ = 21328598. Its totient is φ = 21328596.

The previous prime is 21328561. The next prime is 21328603. The reversal of 21328597 is 79582312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21288996 + 39601 = 4614^2 + 199^2 .

It is a cyclic number.

It is not a de Polignac number, because 21328597 - 2¹⁵ = 21295829 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21328537) 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 as a sum of consecutive naturals, namely, 10664298 + 10664299.

It is an arithmetic number, because the mean of its divisors is an integer number (10664299).

Almost surely, 2^21328597 is an apocalyptic number.

It is an amenable number.

21328597 is a deficient number, since it is larger than the sum of its proper divisors (1).

21328597 is an equidigital number, since it uses as much as digits as its factorization.

21328597 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 30240, while the sum is 37.

The square root of 21328597 is about 4618.2894019323. The cubic root of 21328597 is about 277.3239832829.

The spelling of 21328597 in words is "twenty-one million, three hundred twenty-eight thousand, five hundred ninety-seven".