21662265 has 16 divisors (see below), whose sum is σ = 34845696. Its totient is φ = 11491200.

The previous prime is 21662237. The next prime is 21662281. The reversal of 21662265 is 56226612.

It is not a de Polignac number, because 21662265 - 2¹⁴ = 21645881 is a prime.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 916 + ... + 6645.

It is an arithmetic number, because the mean of its divisors is an integer number (2177856).

Almost surely, 2^21662265 is an apocalyptic number.

It is an amenable number.

21662265 is a deficient number, since it is larger than the sum of its proper divisors (13183431).

21662265 is a wasteful number, since it uses less digits than its factorization.

21662265 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7760.

The product of its digits is 8640, while the sum is 30.

The square root of 21662265 is about 4654.2738423948. The cubic root of 21662265 is about 278.7626737855.

Adding to 21662265 its reverse (56226612), we get a palindrome (77888877).

It can be divided in two parts, 216 and 62265, that added together give a triangular number (62481 = T₃₅₃).

The spelling of 21662265 in words is "twenty-one million, six hundred sixty-two thousand, two hundred sixty-five".