21430165 has 4 divisors (see below), whose sum is σ = 25716204. Its totient is φ = 17144128.

The previous prime is 21430147. The next prime is 21430169. The reversal of 21430165 is 56103412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 16313521 + 5116644 = 4039^2 + 2262^2 .

It is a cyclic number.

It is not a de Polignac number, because 21430165 - 2⁷ = 21430037 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21430169) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2143012 + ... + 2143021.

It is an arithmetic number, because the mean of its divisors is an integer number (6429051).

Almost surely, 2^21430165 is an apocalyptic number.

It is an amenable number.

21430165 is a deficient number, since it is larger than the sum of its proper divisors (4286039).

21430165 is an equidigital number, since it uses as much as digits as its factorization.

21430165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4286038.

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 21430165 is about 4629.2726210497. The cubic root of 21430165 is about 277.7634972510.

Adding to 21430165 its reverse (56103412), we get a palindrome (77533577).

The spelling of 21430165 in words is "twenty-one million, four hundred thirty thousand, one hundred sixty-five".