21151250 has 20 divisors (see below), whose sum is σ = 39648246. Its totient is φ = 8460000.

The previous prime is 21151241. The next prime is 21151253. The reversal of 21151250 is 5215112.

It can be written as a sum of positive squares in 5 ways, for example, as 1018081 + 20133169 = 1009^2 + 4487^2 .

It is not an unprimeable number, because it can be changed into a prime (21151253) 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 9 ways as a sum of consecutive naturals, for example, 7211 + ... + 9710.

Almost surely, 2^21151250 is an apocalyptic number.

21151250 is a deficient number, since it is larger than the sum of its proper divisors (18496996).

21151250 is an equidigital number, since it uses as much as digits as its factorization.

21151250 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16943 (or 16928 counting only the distinct ones).

The product of its (nonzero) digits is 100, while the sum is 17.

The square root of 21151250 is about 4599.0488147007. The cubic root of 21151250 is about 276.5531945436.

Adding to 21151250 its reverse (5215112), we get a palindrome (26366362).

The spelling of 21151250 in words is "twenty-one million, one hundred fifty-one thousand, two hundred fifty".