21218495 has 4 divisors (see below), whose sum is σ = 25462200. Its totient is φ = 16974792.

The previous prime is 21218473. The next prime is 21218503. The reversal of 21218495 is 59481212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21218495 - 2²⁴ = 4441279 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2121845 + ... + 2121854.

It is an arithmetic number, because the mean of its divisors is an integer number (6365550).

Almost surely, 2^21218495 is an apocalyptic number.

21218495 is a deficient number, since it is larger than the sum of its proper divisors (4243705).

21218495 is an equidigital number, since it uses as much as digits as its factorization.

21218495 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4243704.

The product of its digits is 5760, while the sum is 32.

The square root of 21218495 is about 4606.3537640958. The cubic root of 21218495 is about 276.8459612652.

The spelling of 21218495 in words is "twenty-one million, two hundred eighteen thousand, four hundred ninety-five".