21291593 has 2 divisors, whose sum is σ = 21291594. Its totient is φ = 21291592.

The previous prime is 21291547. The next prime is 21291643. The reversal of 21291593 is 39519212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12694969 + 8596624 = 3563^2 + 2932^2 .

It is a cyclic number.

It is not a de Polignac number, because 21291593 - 2⁸ = 21291337 is a prime.

It is not a weakly prime, because it can be changed into another prime (21291503) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10645796 + 10645797.

It is an arithmetic number, because the mean of its divisors is an integer number (10645797).

Almost surely, 2^21291593 is an apocalyptic number.

It is an amenable number.

21291593 is a deficient number, since it is larger than the sum of its proper divisors (1).

21291593 is an equidigital number, since it uses as much as digits as its factorization.

21291593 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4860, while the sum is 32.

The square root of 21291593 is about 4614.2814175124. The cubic root of 21291593 is about 277.1635095749.

The spelling of 21291593 in words is "twenty-one million, two hundred ninety-one thousand, five hundred ninety-three".