21250049 has 4 divisors (see below), whose sum is σ = 21259860. Its totient is φ = 21240240.

The previous prime is 21250039. The next prime is 21250057. The reversal of 21250049 is 94005212.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 5726449 + 15523600 = 2393^2 + 3940^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21250049 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21250039) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 62 + ... + 6519.

It is an arithmetic number, because the mean of its divisors is an integer number (5314965).

It is a Proth number, since it is equal to 1297 ⋅ 2¹⁴ + 1 and 1297 < 2¹⁴.

Almost surely, 2^21250049 is an apocalyptic number.

It is an amenable number.

21250049 is a deficient number, since it is larger than the sum of its proper divisors (9811).

21250049 is an equidigital number, since it uses as much as digits as its factorization.

21250049 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9810.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 21250049 is about 4609.7775434396. Note that the first 3 decimals coincide. The cubic root of 21250049 is about 276.9831257342.

The spelling of 21250049 in words is "twenty-one million, two hundred fifty thousand, forty-nine".