21242415 has 8 divisors (see below), whose sum is σ = 33987888. Its totient is φ = 11329280.

The previous prime is 21242393. The next prime is 21242443. The reversal of 21242415 is 51424212.

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

It is not a de Polignac number, because 21242415 - 2¹⁰ = 21241391 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21242391 and 21242400.

It is a congruent 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, 708066 + ... + 708095.

It is an arithmetic number, because the mean of its divisors is an integer number (4248486).

Almost surely, 2^21242415 is an apocalyptic number.

21242415 is a deficient number, since it is larger than the sum of its proper divisors (12745473).

21242415 is a wasteful number, since it uses less digits than its factorization.

21242415 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1416169.

The product of its digits is 640, while the sum is 21.

The square root of 21242415 is about 4608.9494464574. The cubic root of 21242415 is about 276.9499533803.

Adding to 21242415 its reverse (51424212), we get a palindrome (72666627).

The spelling of 21242415 in words is "twenty-one million, two hundred forty-two thousand, four hundred fifteen".