21273187 has 16 divisors (see below), whose sum is σ = 24054912. Its totient is φ = 18679680.

The previous prime is 21273181. The next prime is 21273191. The reversal of 21273187 is 78137212.

It is not a de Polignac number, because 21273187 - 2¹¹ = 21271139 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21273181) 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 15 ways as a sum of consecutive naturals, for example, 22137 + ... + 23077.

It is an arithmetic number, because the mean of its divisors is an integer number (1503432).

Almost surely, 2^21273187 is an apocalyptic number.

21273187 is a deficient number, since it is larger than the sum of its proper divisors (2781725).

21273187 is a wasteful number, since it uses less digits than its factorization.

21273187 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1038.

The product of its digits is 4704, while the sum is 31.

The square root of 21273187 is about 4612.2865262254. The cubic root of 21273187 is about 277.0836197910.

The spelling of 21273187 in words is "twenty-one million, two hundred seventy-three thousand, one hundred eighty-seven".