21187265 has 8 divisors (see below), whose sum is σ = 27736128. Its totient is φ = 15408880.

The previous prime is 21187259. The next prime is 21187279. The reversal of 21187265 is 56278112.

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

It is not a de Polignac number, because 21187265 - 2¹⁴ = 21170881 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 192557 + ... + 192666.

It is an arithmetic number, because the mean of its divisors is an integer number (3467016).

Almost surely, 2^21187265 is an apocalyptic number.

It is an amenable number.

21187265 is a deficient number, since it is larger than the sum of its proper divisors (6548863).

21187265 is a wasteful number, since it uses less digits than its factorization.

21187265 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 385239.

The product of its digits is 6720, while the sum is 32.

The square root of 21187265 is about 4602.9626329137. The cubic root of 21187265 is about 276.7100712534.

The spelling of 21187265 in words is "twenty-one million, one hundred eighty-seven thousand, two hundred sixty-five".