21399250 has 16 divisors (see below), whose sum is σ = 40059864. Its totient is φ = 8559600.

The previous prime is 21399239. The next prime is 21399299. The reversal of 21399250 is 5299312.

It can be written as a sum of positive squares in 4 ways, for example, as 1212201 + 20187049 = 1101^2 + 4493^2 .

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 42549 + ... + 43048.

Almost surely, 2^21399250 is an apocalyptic number.

21399250 is a deficient number, since it is larger than the sum of its proper divisors (18660614).

21399250 is an equidigital number, since it uses as much as digits as its factorization.

21399250 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85614 (or 85604 counting only the distinct ones).

The product of its (nonzero) digits is 4860, while the sum is 31.

The square root of 21399250 is about 4625.9323384589. The cubic root of 21399250 is about 277.6298664392.

The spelling of 21399250 in words is "twenty-one million, three hundred ninety-nine thousand, two hundred fifty".