21420193 has 4 divisors (see below), whose sum is σ = 21443760. Its totient is φ = 21396628.

The previous prime is 21420169. The next prime is 21420209. The reversal of 21420193 is 39102412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21420193 - 2⁹ = 21419681 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21420103) 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 in 3 ways as a sum of consecutive naturals, for example, 10363 + ... + 12256.

It is an arithmetic number, because the mean of its divisors is an integer number (5360940).

Almost surely, 2^21420193 is an apocalyptic number.

It is an amenable number.

21420193 is a deficient number, since it is larger than the sum of its proper divisors (23567).

21420193 is an equidigital number, since it uses as much as digits as its factorization.

21420193 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23566.

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 21420193 is about 4628.1954366686. The cubic root of 21420193 is about 277.7204070970.

The spelling of 21420193 in words is "twenty-one million, four hundred twenty thousand, one hundred ninety-three".