21540250 has 16 divisors (see below), whose sum is σ = 40323816. Its totient is φ = 8616000.

The previous prime is 21540247. The next prime is 21540269. The reversal of 21540250 is 5204512.

It can be written as a sum of positive squares in 4 ways, for example, as 2556801 + 18983449 = 1599^2 + 4357^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 42831 + ... + 43330.

Almost surely, 2^21540250 is an apocalyptic number.

21540250 is a deficient number, since it is larger than the sum of its proper divisors (18783566).

21540250 is an equidigital number, since it uses as much as digits as its factorization.

21540250 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 86178 (or 86168 counting only the distinct ones).

The product of its (nonzero) digits is 400, while the sum is 19.

The square root of 21540250 is about 4641.1474874216. The cubic root of 21540250 is about 278.2383012685.

Adding to 21540250 its reverse (5204512), we get a palindrome (26744762).

The spelling of 21540250 in words is "twenty-one million, five hundred forty thousand, two hundred fifty".