20398665 has 32 divisors (see below), whose sum is σ = 37610496. Its totient is φ = 9247680.

The previous prime is 20398663. The next prime is 20398699. The reversal of 20398665 is 56689302.

It is not a de Polignac number, because 20398665 - 2¹ = 20398663 is a prime.

It is a super-2 number, since 2×20398665² = 832211067564450, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20398663) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 13014 + ... + 14496.

It is an arithmetic number, because the mean of its divisors is an integer number (1175328).

Almost surely, 2^20398665 is an apocalyptic number.

It is an amenable number.

20398665 is a deficient number, since it is larger than the sum of its proper divisors (17211831).

20398665 is a wasteful number, since it uses less digits than its factorization.

20398665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1629.

The product of its (nonzero) digits is 77760, while the sum is 39.

The square root of 20398665 is about 4516.4881268525. The cubic root of 20398665 is about 273.2334811093.

The spelling of 20398665 in words is "twenty million, three hundred ninety-eight thousand, six hundred sixty-five".