21455393 has 2 divisors, whose sum is σ = 21455394. Its totient is φ = 21455392.

The previous prime is 21455383. The next prime is 21455429. The reversal of 21455393 is 39355412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19430464 + 2024929 = 4408^2 + 1423^2 .

It is a cyclic number.

It is not a de Polignac number, because 21455393 - 2¹⁶ = 21389857 is a prime.

It is not a weakly prime, because it can be changed into another prime (21455353) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10727696 + 10727697.

It is an arithmetic number, because the mean of its divisors is an integer number (10727697).

Almost surely, 2^21455393 is an apocalyptic number.

It is an amenable number.

21455393 is a deficient number, since it is larger than the sum of its proper divisors (1).

21455393 is an equidigital number, since it uses as much as digits as its factorization.

21455393 is an evil number, because the sum of its binary digits is even.

The product of its digits is 16200, while the sum is 32.

The square root of 21455393 is about 4631.9966537121. The cubic root of 21455393 is about 277.8724506749.

The spelling of 21455393 in words is "twenty-one million, four hundred fifty-five thousand, three hundred ninety-three".