21642285 has 32 divisors (see below), whose sum is σ = 40331520. Its totient is φ = 9704448.

The previous prime is 21642281. The next prime is 21642289. The reversal of 21642285 is 58224612.

It is an interprime number because it is at equal distance from previous prime (21642281) and next prime (21642289).

It is not a de Polignac number, because 21642285 - 2² = 21642281 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21642281) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3621 + ... + 7509.

It is an arithmetic number, because the mean of its divisors is an integer number (1260360).

Almost surely, 2^21642285 is an apocalyptic number.

It is an amenable number.

21642285 is a deficient number, since it is larger than the sum of its proper divisors (18689235).

21642285 is a wasteful number, since it uses less digits than its factorization.

21642285 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3957.

The product of its digits is 7680, while the sum is 30.

The square root of 21642285 is about 4652.1269329200. The cubic root of 21642285 is about 278.6769426538.

Adding to 21642285 its reverse (58224612), we get a palindrome (79866897).

The spelling of 21642285 in words is "twenty-one million, six hundred forty-two thousand, two hundred eighty-five".