21250145 has 8 divisors (see below), whose sum is σ = 29143104. Its totient is φ = 14571504.

The previous prime is 21250139. The next prime is 21250171. The reversal of 21250145 is 54105212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21250145 - 2⁴ = 21250129 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 303539 + ... + 303608.

It is an arithmetic number, because the mean of its divisors is an integer number (3642888).

Almost surely, 2^21250145 is an apocalyptic number.

It is an amenable number.

21250145 is a deficient number, since it is larger than the sum of its proper divisors (7892959).

21250145 is an equidigital number, since it uses as much as digits as its factorization.

21250145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 607159.

The product of its (nonzero) digits is 400, while the sum is 20.

The square root of 21250145 is about 4609.7879560778. The cubic root of 21250145 is about 276.9835428366.

Adding to 21250145 its reverse (54105212), we get a palindrome (75355357).

The spelling of 21250145 in words is "twenty-one million, two hundred fifty thousand, one hundred forty-five".