21421365 has 16 divisors (see below), whose sum is σ = 39170688. Its totient is φ = 9792576.

The previous prime is 21421333. The next prime is 21421373. The reversal of 21421365 is 56312412.

It is not a de Polignac number, because 21421365 - 2⁵ = 21421333 is a prime.

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, 101902 + ... + 102111.

It is an arithmetic number, because the mean of its divisors is an integer number (2448168).

Almost surely, 2^21421365 is an apocalyptic number.

It is an amenable number.

21421365 is a deficient number, since it is larger than the sum of its proper divisors (17749323).

21421365 is a wasteful number, since it uses less digits than its factorization.

21421365 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 204028.

The product of its digits is 1440, while the sum is 24.

The square root of 21421365 is about 4628.3220501603. The cubic root of 21421365 is about 277.7254721366.

Adding to 21421365 its reverse (56312412), we get a palindrome (77733777).

The spelling of 21421365 in words is "twenty-one million, four hundred twenty-one thousand, three hundred sixty-five".