21261250 has 40 divisors (see below), whose sum is σ = 40571388. Its totient is φ = 8352000.

The previous prime is 21261241. The next prime is 21261259. The reversal of 21261250 is 5216212.

It is an interprime number because it is at equal distance from previous prime (21261241) and next prime (21261259).

It can be written as a sum of positive squares in 10 ways, for example, as 3359889 + 17901361 = 1833^2 + 4231^2 .

It is not an unprimeable number, because it can be changed into a prime (21261259) 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 19 ways as a sum of consecutive naturals, for example, 91134 + ... + 91366.

Almost surely, 2^21261250 is an apocalyptic number.

21261250 is a deficient number, since it is larger than the sum of its proper divisors (19310138).

21261250 is an equidigital number, since it uses as much as digits as its factorization.

21261250 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 328 (or 313 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 21261250 is about 4610.9923010129. The cubic root of 21261250 is about 277.0317835521.

Adding to 21261250 its reverse (5216212), we get a palindrome (26477462).

The spelling of 21261250 in words is "twenty-one million, two hundred sixty-one thousand, two hundred fifty".