21642117 has 16 divisors (see below), whose sum is σ = 33234432. Its totient is φ = 12270960.

The previous prime is 21642113. The next prime is 21642119. The reversal of 21642117 is 71124612.

It is not a de Polignac number, because 21642117 - 2² = 21642113 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21642113) 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, 1183 + ... + 6684.

It is an arithmetic number, because the mean of its divisors is an integer number (2077152).

Almost surely, 2^21642117 is an apocalyptic number.

It is an amenable number.

21642117 is a deficient number, since it is larger than the sum of its proper divisors (11592315).

21642117 is a wasteful number, since it uses less digits than its factorization.

21642117 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8008.

The product of its digits is 672, while the sum is 24.

The square root of 21642117 is about 4652.1088766279. The cubic root of 21642117 is about 278.6762215677.

Adding to 21642117 its reverse (71124612), we get a palindrome (92766729).

The spelling of 21642117 in words is "twenty-one million, six hundred forty-two thousand, one hundred seventeen".