21724193 has 2 divisors, whose sum is σ = 21724194. Its totient is φ = 21724192.

The previous prime is 21724189. The next prime is 21724207. The reversal of 21724193 is 39142712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21418384 + 305809 = 4628^2 + 553^2 .

It is a cyclic number.

It is not a de Polignac number, because 21724193 - 2² = 21724189 is a prime.

It is equal to p_1372880 and since 21724193 and 1372880 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (21724133) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10862096 + 10862097.

It is an arithmetic number, because the mean of its divisors is an integer number (10862097).

Almost surely, 2^21724193 is an apocalyptic number.

It is an amenable number.

21724193 is a deficient number, since it is larger than the sum of its proper divisors (1).

21724193 is an equidigital number, since it uses as much as digits as its factorization.

21724193 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3024, while the sum is 29.

The square root of 21724193 is about 4660.9219045163. The cubic root of 21724193 is about 279.0280629352.

The spelling of 21724193 in words is "twenty-one million, seven hundred twenty-four thousand, one hundred ninety-three".