21790250 has 32 divisors (see below), whose sum is σ = 41760576. Its totient is φ = 8509200.

The previous prime is 21790247. The next prime is 21790267. The reversal of 21790250 is 5209712.

It is a Curzon number.

It is a plaindrome in base 11.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 9737 + ... + 11763.

It is an arithmetic number, because the mean of its divisors is an integer number (1305018).

Almost surely, 2^21790250 is an apocalyptic number.

21790250 is a deficient number, since it is larger than the sum of its proper divisors (19970326).

21790250 is a wasteful number, since it uses less digits than its factorization.

21790250 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2087 (or 2077 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 26.

The square root of 21790250 is about 4668.0027849178. The cubic root of 21790250 is about 279.3105913643.

Subtracting from 21790250 its sum of digits (26), we obtain a square (21790224 = 4668²).

Adding to 21790250 its reverse (5209712), we get a palindrome (26999962).

The spelling of 21790250 in words is "twenty-one million, seven hundred ninety thousand, two hundred fifty".