21248215 has 16 divisors (see below), whose sum is σ = 27106272. Its totient is φ = 15934464.

The previous prime is 21248207. The next prime is 21248221. The reversal of 21248215 is 51284212.

It is a cyclic number.

It is not a de Polignac number, because 21248215 - 2³ = 21248207 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21248215.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 38572 + ... + 39118.

It is an arithmetic number, because the mean of its divisors is an integer number (1694142).

Almost surely, 2^21248215 is an apocalyptic number.

21248215 is a deficient number, since it is larger than the sum of its proper divisors (5858057).

21248215 is a wasteful number, since it uses less digits than its factorization.

21248215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1026.

The product of its digits is 1280, while the sum is 25.

The square root of 21248215 is about 4609.5786141469. The cubic root of 21248215 is about 276.9751570990.

The spelling of 21248215 in words is "twenty-one million, two hundred forty-eight thousand, two hundred fifteen".