20213665 has 16 divisors (see below), whose sum is σ = 25515648. Its totient is φ = 15342976.

The previous prime is 20213659. The next prime is 20213681. The reversal of 20213665 is 56631202.

It is a cyclic number.

It is not a de Polignac number, because 20213665 - 2³ = 20213657 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15114 + ... + 16396.

It is an arithmetic number, because the mean of its divisors is an integer number (1594728).

Almost surely, 2^20213665 is an apocalyptic number.

It is an amenable number.

20213665 is a deficient number, since it is larger than the sum of its proper divisors (5301983).

20213665 is a wasteful number, since it uses less digits than its factorization.

20213665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1448.

The product of its (nonzero) digits is 2160, while the sum is 25.

The square root of 20213665 is about 4495.9609651330. The cubic root of 20213665 is about 272.4049664403.

Adding to 20213665 its reverse (56631202), we get a palindrome (76844867).

The spelling of 20213665 in words is "twenty million, two hundred thirteen thousand, six hundred sixty-five".