21097513 has 2 divisors, whose sum is σ = 21097514. Its totient is φ = 21097512.

The previous prime is 21097487. The next prime is 21097547. The reversal of 21097513 is 31579012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18045504 + 3052009 = 4248^2 + 1747^2 .

It is a cyclic number.

It is not a de Polignac number, because 21097513 - 2⁵ = 21097481 is a prime.

It is not a weakly prime, because it can be changed into another prime (21097613) 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, 10548756 + 10548757.

It is an arithmetic number, because the mean of its divisors is an integer number (10548757).

Almost surely, 2^21097513 is an apocalyptic number.

It is an amenable number.

21097513 is a deficient number, since it is larger than the sum of its proper divisors (1).

21097513 is an equidigital number, since it uses as much as digits as its factorization.

21097513 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1890, while the sum is 28.

The square root of 21097513 is about 4593.2029130009. The cubic root of 21097513 is about 276.3187916558.

The spelling of 21097513 in words is "twenty-one million, ninety-seven thousand, five hundred thirteen".