21745413 has 6 divisors (see below), whose sum is σ = 31410054. Its totient is φ = 14496936.

The previous prime is 21745403. The next prime is 21745417. The reversal of 21745413 is 31454712.

It can be written as a sum of positive squares in only one way, i.e., 21178404 + 567009 = 4602^2 + 753^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21745413 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21745417) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1208070 + ... + 1208087.

It is an arithmetic number, because the mean of its divisors is an integer number (5235009).

Almost surely, 2^21745413 is an apocalyptic number.

It is an amenable number.

21745413 is a deficient number, since it is larger than the sum of its proper divisors (9664641).

21745413 is a wasteful number, since it uses less digits than its factorization.

21745413 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2416163 (or 2416160 counting only the distinct ones).

The product of its digits is 3360, while the sum is 27.

The square root of 21745413 is about 4663.1977225934. The cubic root of 21745413 is about 279.1188840870.

The spelling of 21745413 in words is "twenty-one million, seven hundred forty-five thousand, four hundred thirteen".