21427315 has 16 divisors (see below), whose sum is σ = 31647168. Its totient is φ = 13562496.

The previous prime is 21427309. The next prime is 21427319. The reversal of 21427315 is 51372412.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21427315 - 2⁷ = 21427187 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21427315.

It is not an unprimeable number, because it can be changed into a prime (21427319) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 23092 + ... + 24001.

It is an arithmetic number, because the mean of its divisors is an integer number (1977948).

Almost surely, 2^21427315 is an apocalyptic number.

21427315 is a deficient number, since it is larger than the sum of its proper divisors (10219853).

21427315 is a wasteful number, since it uses less digits than its factorization.

21427315 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47118.

The product of its digits is 1680, while the sum is 25.

The square root of 21427315 is about 4628.9647870771. The cubic root of 21427315 is about 277.7511834391.

Adding to 21427315 its reverse (51372412), we get a palindrome (72799727).

The spelling of 21427315 in words is "twenty-one million, four hundred twenty-seven thousand, three hundred fifteen".