21442165 has 32 divisors (see below), whose sum is σ = 28828800. Its totient is φ = 15240960.

The previous prime is 21442163. The next prime is 21442229. The reversal of 21442165 is 56124412.

21442165 = 150² + 151² + ... + 407².

It is a happy number.

It is not a de Polignac number, because 21442165 - 2¹ = 21442163 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21442163) 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, 118375 + ... + 118555.

It is an arithmetic number, because the mean of its divisors is an integer number (900900).

Almost surely, 2^21442165 is an apocalyptic number.

It is an amenable number.

21442165 is a deficient number, since it is larger than the sum of its proper divisors (7386635).

21442165 is a wasteful number, since it uses less digits than its factorization.

21442165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 277.

The product of its digits is 1920, while the sum is 25.

The square root of 21442165 is about 4630.5685396072. The cubic root of 21442165 is about 277.8153329076.

Adding to 21442165 its reverse (56124412), we get a palindrome (77566577).

The spelling of 21442165 in words is "twenty-one million, four hundred forty-two thousand, one hundred sixty-five".